Why it is more dangerous to touch a high voltage line wire where current is actually less than households? I have seen that power is transmitted from power stations to households at high voltage and low current to minimize the power loss.
That means the current in the transmission line is less than the current in the household wiring as there using a transformer we decrease the voltage and current is increased to keep the same power.
As it's the current that is dangerous, as it means how much charge flows per time unit: why are transmission lines more dangerous than household lines, even though voltage is high, but current is less?
 A: The current in the transmission wires is lower for a given amount of power being delivered than current in lower-voltage wires transmitting the same amount of power. It can still supply many, many times more current than is needed to electrocute you.
You seem to have a misconception that the current and power are fixed. The wire supplies whatever current that the attached loads allow to pass. With no load, there's no current and no power delivered, with a heavy load, there's a lot of current and a lot of power...it's voltage that's (roughly) fixed. By becoming part of the circuit, you become another load, and a high-voltage wire will easily supply a little more current to pass through you.
Higher voltages are more hazardous in general because a higher voltage can drive a lethal current through a higher-resistance path that includes your body, and high enough voltages can cause insulators (including air) to break down and stop protecting you.
A: Current flowing in the wire is irrelevant to the danger.
It's the current flowing through your body that will hurt you, and the amount of current that flows through your body will be proportional to the voltage between the wire and anything else that you happened to be touching (e.g., the ground upon which you are standing.)
A: The current that damages a body is far below the current capability of any typical power line (milliamperes vs amperes). Also, the body's resistance is quite high. So, any power line with sufficient voltage will be capable of giving a body a deadly amount of current. Therefore it is the voltage of the power line, alone, that dictates how much current will go through the body. Only when the source of power has an extremely low maximum current (like, say, an electric fencer or a small bug zapper) will a body drain the power and thus cause the voltage to drop.
A: First, a word of clarification. "Less current than there otherwise would have been" doesn't mean that the current is actually "low". Remember that HV lines service multiple houses, so the current flow through them is still typically higher than what flows into a single average home.
However, the current that flows through the wire isn't what makes it dangerous to touch the wire or not*. What's important is the current that flows through you when you touch the wire. So, the question becomes, "how much current would flow through you if you touched the wire?"
All else being equal, the current that flows through you is directly proportional to the voltage across you. Double the voltage, double the current. And that's why it's dangerous to touch a high-voltage low-current wire: The high voltage will push current through you regardless of what the previous current flow was.
However, that's not the whole story. The fact is, there's no such thing as a perfectly constant voltage source. Your body would represent an additional load to whatever the source of electricity is, which would tend to pull the voltage down. High-voltage air ionizers and ozone generators are (usually) perfectly safe to touch, because their power supply circuitry has next to zero current delivering capability, so touching it cuts the voltage to a tiny fraction of what it was with no load. Electric fences (for cattle or pets) have a somewhat higher capacity, so the voltage drops enough that its not dangerous, but still enough to give you a little zing. For electrical power lines, though, the load presented by your body is incredibly tiny compared to what they normally supply, so the voltage drop is undetectably minuscule, and you get the full voltage across your body with all the current that that implies.
* Well, high current flow through a wire results in a lot of waste heat being generated, so I suppose, technically speaking, a high current could be dangerous in that you could be burned by it.
A: Because the increased voltage is better at overcoming what little electrical resistance the surface of the body (and any attempt at insulation) provides, and will drive a higher current through the squishy stuff that you presumably value.
And there's a risk of a flashover arc, and if that happens your remains will be sufficiently charred that they won't be getting an open-casket funeral.
A: It's for multiple reasons.
First of, 30 mA through the chest is the danger territory. Things can happen before this, but that's generally where it's really dangerous. Dry skin can have 10 kohm resistance or more - so with 110 V or 220 V it's borderline if you get into the really dangerous territory.
If you get current through an arm, or other body parts, but not through the chest, you'll almost certainly walk away from 220 V.
If we jump to a 22 kV line, and assume a 10 kohm skin resistance, the current is no longer under 30 mA - it's a whopping 2 A - well above what's fatal. And it's no longer depositing tens of watts. It's depositing tens of kilowatts. Close to 50 kW if we assume a static 10 kohm resistance.
This leads to internal and external burns. Those burns may lead to kidney failure as well. Even if you only get current through a body part other than your chest, you'll have severe burns.

That means the current in the transmission line is less than the current in the household wiring as there using a transformer we decrease the voltage and current is increased to keep the same power.

This is mistaken. The voltage is high to reduce losses, but you don't have a 22 kV distribution line to your home. You have it to your neighbourhood. It's not uncommon to have hundreds of amperes available at a high voltage line. In addition, the short circuit performance is likely to provide a higher short circuit power than what you receive in your outlets at home, as the impedance in the system is likely to be low.
A: Your language is imprecise. Voltage is not a property of a location, it's a property of two locations; it's the difference between the electrical potential between two points. It's not quite true that "it's the current that is dangerous", as the current is not the only factor, and to the extent that it is accurate, it needs the qualifier "the current through your body". The current flowing through a point that you are touching, by itself, is completely irrelevant to how much danger you're in (a wire with more current may be more dangerous, but the danger comes from the voltage causing the current, not the current itself). If you have less resistance than the power line (including the transformers), which you almost certainly do, then the current through you will be higher than the current through the wire, so the low level of current in the wire says little about how much danger you are in.

That means the current in the transmission line is less than the current in the household wiring as there using a transformer we decrease the voltage and current is increased to keep the same power.

That doesn't follow. If several households are connected in parallel to the power lines, then the current in the households could be less than the current through the power line.
