Depending on how bad the vibrations are there are a few things you could try. First you could try putting some foam or rubber spacers in between the camera and mount.
For something as persistent as vibrations from an HVAC system it may be worth trying a vibration damping mount.
Customers have used one made by NigelBDesign in the past. https://www.nigelbdesign.com/pdfs/Anti%20Vibration%20Multi%20Camera%20Mounting%20Bracket.pdf
But a lot of times when there are real strong vibrations passing to the camera, the best option is relocating the camera to a new position.
Does anyone have a suggestion for preventing camera vibrations from a wall mounted PTZ? It was mounted using the PTZ wall mount but anytime the A/C comes on, the wall shakes and with it, the video signal.