Since Einstein has shown that gravitational force is created by the warping of Space-Time, why are physicists looking for the "graviton" particle?
Since gravitational force is created by a warping of Space-Time, isn't it logical for electric & magnetic forces to be also created by warping Space-Time? Perhaps in a different dimension(s)?
The fact is not that you just see that gravity warps spacetime, but that if you include into the dynamics of your theory space-time deformations, you get gravity as a result.
Electromagnetism comes from another kind of deformation: you can say they arise through the "deformation" of the (local, pointwise) definition of electric charge.
The idea is that nature is invariant with respect to a certain symmetry (here for instance something similar to swapping the sign of all the charges) and you can even extend this symmetry to be local (i.e. you do a transformation which depends on the space-time coordinate of each point). Going in more detail at this level seems inappropriate. You can have a look to this page if you feel like reading some more https://en.wikipedia.org/wiki/Gauge_theory#Description .
In the case of gravity the starting-point symmetry is something similar to changes of reference frames.
These settings in which a different symmetry transformation can be done at each point are called gauge theories.