I was under the impression that the no-fly zone was to protect the civilians. I don't consider this an act of flexing its muscles when there are reports that the dictator is launching air strikes against the population. I admit that I haven't thoroughly researched this, though.

Here are the details on Resolution 1973 which declares a ceasefire and establishes the no-fly zone. 10 nations voted for, 5 abstained (incl. China & Russia), and 0 against, thus it passed.