Is it safe to mount a medium-sized air compressor to the floor to stop or limit vibrations?
If the compressor is equipped with anchoring tabs it can be anchored to the floor. Install some pieces of rubber between the floor and the mounting tabs. Cut the rubber pieces from and old tire,rubber mat etc. Use locking nuts on the anchor bolts and don't tighten them so much that the rubber is completely compressed. If there are not mounting tabs on the compressor than I would build a wood box will restrict the wheels and what ever else hits the floor. Then anchor the box to the concrete pad.