noise at idle

my car is 2003 elantra ve. When i stop at traffic light in the first minutes after car started (especially in cold weather), i hear noise coming from front end. Sounds like engine mount touch body or exhaust pipe leaking (something resonance). When i release the brake pedal, the noise is gone. I checked engine mount, drive belt, exhaust pipe, nothing was found. Anybody get the same problem. Any idea? Thanks.