07 Honda Civic ex 2.0 idle drops when AC is on

That's pretty much normal. The additional load of the A/C will labor the engine more. The idle air control should automatically compensate for that and increase the idle RPM. If the engine has any other issues, they would be more obvious in this situation. Here are a couple things you can try.
You may have a bad IAC ( idle air control) but try eliminating any vacuum leaks and cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.