Netanyahu is saying that for show. It gives the Israeli government a blanket justification to ignore any collateral damage caused in this conflict because they will just claim that they warned them to leave.
Does anybody really believe that the insanely sophisticated security apparatus of Mossad didn’t know these attacks were coming in advance? This has the same stink of the Bush administration ignoring repeated warnings of attacks by Al Qaeda pre-9/11 to justify war in the middle east all over again.