My iPhone 3 vibrates really loud, kind of like a rattling?

I have has my iPhone 3 for at least a few months and i haven't dropped it much, only from really small distances on carpet and leately it has been vibrating really loud, almost like a rattling sound. Every time i have my vibrate on it makes me feel like my iPhone is breaking. I turned off the vibrate but it doesn't feel right. Can anyone help?
(Please no "I have this problem too!" I just want an answer please and thank you.)

The vibration system is a physical system, and not adjustable, if yours is making more noise and such than normal, there's nothing you can do about it other than possibly getting it serviced.