The Israeli leadership knew that it could not reply to Hamas’s microwar without engaging in total war on the Gaza population, and that this step would be unpopular with the world’s publics. But the Israeli leadership has successfully thumbed its nose and world public opinion so often and so successfully that this sort of consideration does not even enter into their practical calculations (except to the extent that they are careful to do a lot of propaganda for their war effort). Their estimation that they will suffer no practical bad consequences of attacks on civilians is certainly correct in the short to medium term.
The Israel lobbies are wealthy and powerful, and the US congress depends heavily on them for campaign funding. If the US legislators voted on the Gaza operation, they would support Israel except for the same 10 who objected to the war on Lebanon (the 10 are mostly from congressional districts with a lot of Arab-Americans). Israel will suffer no practical sanctions from any government. Egypt and Jordan are afraid of Hamas and are more or less handmaidens of Israeli policy toward Gaza. Syria and Lebanon are weak. Iran, for all the hype it generates, is distant and relatively helpless to intervene. European governments have largely ceded the Palestinian-Israeli issue to the US and Israel.