Car vibrates

Car details - 2001 honda civic, automatic transmission, with 110,000 Miles, 4 wheel drive

i had a problem starting the car and the mechanic said its a alternator problem and replaced it today. But when I drove home from the workshop, I realized the car is having a new problem. When I stop the car, it vibrates. I can feel the vibration very much on the brake pedal. I dont feel any noticable vibration when the car is moving.
Please let me know whether the vibration is anything to do with the alternator replacement. My car was pretty smooth and in excellent condition before I did this alternator replacement.
If it cannot be because of this alternator replacemnet, please let me know the possible reason.

thanks a lot.