A provocative Israel will lose the support of the world, probably including the US, especially if they use nukes, and its very existence depends on that support. I don't know if the powers that be in Israel are foolish enough to think otherwise, but if Israel attacks anyone, unless it is in retaliation, Israel won't exist anymore because their allies will bail on them.
Iran is not a threat, either. Just like Israel, I don't know if the powers that be in Iran are foolish enough to think otherwise, but if Iran fires a nuke, even in self-defense in response to an attack, Iran won't exist anymore. There will be more than adequate retaliation to destroy Iran, even without Team America World Police to do the dirty work, although I'd be surprised if we didn't participate in (if not lead) any such effort. I am critical of paranoid, trigger-happy neocons, but fuck, I can't say military intervention isn't necessary when a bunch of fundies start firing nukes. A pre-emptive strike on Iran is foolish without certain knowledge they're going to attack us first, but it would be equally foolish to ignore or "negotiate" with a nuclear Iran on a warpath, even if they're not directly targeting us.
So, yeah, TL;DR: Israel and Iran probably aren't going to do shit, because if they do, they're going to be in a world of hurt.