Given what we know about Iran, war cannot be avoided indefinitely. If we pressure Israel not to strike, the time would come when it would be too late to do so.
To think Iran can be talked out of taking the course they are already on is downright naive. Obama wants to avoid war alright, but only insofar as it benefits HIM to do so.
How allowing the Iranians to buy time would eventually affect Israel does not seem to be a matter of any importance. Truces in Islam are NEVER permanent. Muhammad set the standard by buying himself some time with a false peace agreement, which he broke when he was fully prepared to take agressive action.
Iran will employ similar measures to try to convince the west that they can be placated. And then when no one expects it -- a nuclear attack will be carried out.