2005 Honda Civic Air Conditioning Revs Down

The problem is on a Honda Civic 2005 3dr SI Hatckback.
Normally when the a/c is working well and is turned on there's no problem with engine revs and it's almost transparent, "something" control the engine revs to avoid them down. In my case "something" doesn't work because it feels like the a/c get power from engine and the revs coming down causing engine vibration and the feeling the engine will power off. It only happen when a/c is on. I hope somebody can give me a tip to solve it.

best regards