Do keep up.
UN 1973 specifically states:
4. Authorises member states that have notified the secretary-general, acting nationally or through regional organizations or arrangements, and acting in co-operation with the secretary-general, to take all necessary measures, notwithstanding paragraph 9 of resolution 1970 (2011), to protect civilians and civilian populated areas under threat of attack in the Libyan Arab Jamahiriya, including Benghazi, while excluding a foreign occupation force of any form on any part of Libyan territory, and requests the member states concerned to inform the secretary-general immediately of the measures they take pursuant to the authorization conferred by this paragraph which shall be immediately reported to the Security Council;
Tanks outside a rebel town are an obvious threat to civilian populations, based on Qaddaffi's track record. Taking out AD assets is just another necessary step to establishing a NFZ to defend the civilians, which is the ultimate objective. UN aircrew can and should take out anything that is a threat (direct or otherwise) to innocent civilians.
If you think this includes the Tripoli MacDonalds on the basis of it being bad for civilians, then you're probably right, but that's what the UN signed up for.