Car engine moves when changing car gear from D to R

Hi, my car engine moves. I have gone to the mechanic he changed right side mount of the car the rest of the mounts he said are good. But when I went to the mechanic to see my car I changed the the gear from d to r the engine moved and I can feel because the engine moves too much. Full engine move back and forth. I do not know what to do I have wasted too much money but still problem is there.