This is a high-frequency vibration which occurs at higher engine speeds, but is unrelated to the vehicle speed. You can feel it with the sole of your foot as it rests on the accelerator pedal, but the pedal does not pulsate greatly in the depressing direction of the pedal.
1.Main causes
Engine vibration
Vibrations and resonances in the accelerator cable or linkage
Lack of rigidity in the accelerator cable or linkage
2.Mechanics of vibration development
(1)Engine vibration causes the accelerator cable or linkage to vibrate.
(2)The cable or linkage vibrations are transmitted to the accelerator pedal, causing it to vibrate.
In addition to vibration coming directly from the engine, there is also vibration transmitted from the transmission throttle cable to the accelerator cable or linkage.