Iran has its nuclear sites in 3 different locations, deep underground and heavily fortified. Israel has neither the bombs capable of penetrating that deep, nor the resources for a successful one time strike. The only ones capable of it are the US, but even they would require a constant and maintained bombing of all 3 sites simultaneously. Literally, they would need to "dig" holes with bombs until they reach they completely destroy their sites beyond repair.
UN aid chief says no warring parties observed Yemen truce (Reuters)
from the article: Iran will be able to build nuclear bomb within months, IAEA says