... so you're saying that they "shake" regardless of what device you use them with? If that's the case, then it may be possible that the EarPod's driver is damaged or faulty.
Was this always an issue or just started to happen recently? If the latter, per chance do you listen to audio, with heavy bass settings at loud volumes?
Regardless, AFAIK, Apple does not repair them. If you feel that this may be a manufacturing defect, they are covered under the Apple one-year hardware warranty ... but you would need to have them examined by an Apple Technician to verify that fact before you can expect to get a replacement pair at little or no cost to you.