Isn't an Israeli attack on the Iranian nuclear facilities justified and understandable?

The way I see it, Iran has made plenty of threats to destroy Israel as a whole, and Jews in general, supports all of Israel's enemies, including terrorist organizations, has sent its secret forces to bomb Israel's embassy in Argentina, and is practically a dictatorship (not a real democracy as we've seen three years ago) headed by a religious extremist.
Wouldn't preventing them from developing nuclear weapons be an act of self-defense? Their intentions are clear (threats have been made) and no one can trust the rationality of their leaders so if they were to hold nuclear weapons, using them against Israel (or against other countries in the world, but let's ignore that for now) wouldn't be out of the question.

Please answer based on Israel's point of view, excluding how it would affect the region, your country, etc. Imagine you're the Israeli Prime Minister, whose number one responsibility is to do whats right for his country, i.e. its survival and protection.