Iran once said Israel does not have the right to exist. So Iran have the right to exist but not Israel?
Now, it is one thing to opine but another thing to act. Iran have the right to say anything, even that Israel is an illegitimate state or does not have the right to exist. But the moment Iran act -- war -- against Israel, Israel have the right to self defense and if that mean denying Iran nuclear weapons, they will do whatever they can. If Israel have allies who will ensure military supremacy over neighbors, too bad for the neighbors. Unfair? Tough shid. If you are trying to kill someone, be prepared to take the consequences no matter how unfair it maybe. Many UN members do not recognize Israel as a state. So what? Just do not act on that opinion. For reasons that you may not like, the US is an ally to Israel. Unfair? Too bad the Soviets died.
So, if you have %60 U-235 enrichment, and you loudly proclaim 'Death to...' be prepared to deal with the consequences.