Based on all the information to date:
The US and Israel are working hand in hand to destroy Iran's quest to attain a nuclear deterrent. Western nations like France, England, Germany etc, will support this action against Iran noting Arabs/Muslims are regarded by them as lesser beings and after all Iran is not in their "group". A bit like how they support Israel militarily and politically against the Palestinians who they perceive as lesser beings "untermenchen". i.e. Iraq had no nuclear weapons but it was utterly destroyed with western nations supporting. Iran has no nuclear weapons but may also be utterly destroyed, with western nations supporting the US and Israel. It's simply not in western nations interests to have any moral fiber. The fact that Israel has closed multiple diplomatic missions all over the world suggests that they are in this for the long haul. Iran DOES NOT have the ability to defeat Israel therefore Israel will likely achieve its goal, with no country prepared to defend Iran. The most likely outcome from this is that Russia and China will strengthen military ties.
In hindsight, Iran was in a no-win situation from the get-go. All attempts by Israel to provoke Iran up to this point failed. With action now being taken to cripple Iran forever, Iran now has to choose to either die fighting or simply be destroyed.
Finally, as a foot note, the idea of someone detonating a nuclear devise in Tel Aviv in retaliation is not plausible. I would go so far as to say that Israel has a 100% chance of winning any type of conflict with Iran.
You say that as if religious zealots are rational actors like every other head of state. Is there a great potential and foreseeable need for Iran to be able to deter attack? Of course. But is there also a much greater than zero chance that such weapons find their way into Israel via Iranian non-state actors? Also yes.