guys i finally got it done. it was the main engine mount which gave the vibration and i discovered it. when i took it to mazna motors, laliths bro told me that the mounts are good and need to do a tune up. to be frank i didn't agree. anyway i got the main engine mount removed and to see it was broken. i guess certain things cannot be guessed, but a vibration like that, definitely i knew it should be the mount.
anyway job done.