Mine never did that, until I replaced the stock clutch, throwout bearing, and pressure plate for a SPEC stage I clutch and lightened pressure plate. I also had my flywheel resurfaced.
Does the vibration go away if you push in the clutch all the way? If it does, that means that mechanically you are fine. Mine vibrates all the time, sometimes i'll be idling and i'll hear a grinding sort of sound. I am told it's the pressure plates fingers not all lining up, and while its an earsore, mechanically it's not harming anything. On the other hand, some guys are saying this can wear out your throwout bearing faster, and you need a firewall adjuster or something to fix the problem.
Anyways, try searching, or maybe someone else will respond her. I know this topic was discussed about a week ago, and people were posting a lot of info. The vibration really p!sses me off at points. It sounds like chattering teeth at times. Sometimes you can even here it chattering outside the car at idle, easily over my exhaust. It sounds nasty too, not the kind of sound I want to be heard.