I don't think Obama and Biden are in a diagreement. What is happening here is the following: USA is economicaly and militarillly and diplomatically weakened, thay don't want to afford another war with Muslims. But, even if Obama is a leftist and pro-Muslim, he is a politician and his career is more important to him than his feelings, and surelly as a leftist liberal he also fears Iran (Most leftists hypocritically support those regimes but, if they are clever, they won't wish the danger spread to the rest of the world). USA has realised that Muslims cannot be apeassed by any means, so they just want to show Obama as a peacenik, and Biden as a hardliner just for political correctennes and balance. That way USA's image is not damaged before leftist Europeans.
Israel attacks Iran with no poltical cost for USA, while America is free to attack North Korea if neccessary. They would have the support of nearly all capitalist countries in Asia.
And Muslims... what shall they do? Perhaps blame USA anyway, but do nothing. They know very well that they have no development and depend on oil, but they cannot eat oil!!! So they will never boycott the West.
Perhaps, in this specific situation, Obama is better than the Republicans both for USA and Israel. A Republican would press on Israel to appease leftist anti-Israeli media, Obama does not need to do so. Nobody doubts he is a Leftist and the world media with be with him no matter what he does. He can simply state that he disagrees with the Israeli attack on Iran, and stay quiet.