Blowing a little bit of white smoke

i drive a manual excel lately my car has been blowing a little white smoke whenever i rev the engine even when its not hot weather it still seems to blow a little white smoke. i gave the car a little service i replaced the spark plugs and oil and all that stuff not sure if this is a bad thing or something little ? i haven't used my air con also in a while i put air con on could that be the issue