Vibration of a rotor positioned within a stator of an electric motor of an electric submersible pump assembly is attenuated in a first embodiment by adjusting the length of the rotor to position rotor bearings supporting the rotor within the stator at locations of low amplitude vibration. In a second embodiment, hydraulic pressure is applied to a fluid chamber supporting a thrust bearing that supports the rotor. When hydraulic fluid pressure is applied, the thrust bearing and the rotor move axially. Thus, moving the rotor bearings away from areas of high amplitude vibration of the rotor. In a third embodiment, a sliding mass affixed to the motor is moved in response to vibration of the motor. Movement of the sliding mass changes the vibration profile of the motor.