Is this increasing amount of "collateral damage" in Libya making the war less legitimate?

Obama's justification for American participation was to "prevent a massacre" of innocent people. However, given the increasing incidents of innocent civilians killed by NATO airstrikes - 9 killed in the latest blunder, which NATO admits - America will soon be responsible for a massacre of its own if the war continues, if not already - the Libyan government claims almost 1000 civilians have been killed by NATO forces thus far. Is Obama's justification less legitimate given the rising civilian body count?