Iran has pledged to destroy Israel. Their president has stated that they will do that on numerous occasions. Therefore, the Israeli's can't allow them to attain nuclear weapons or they risk their own survival. This means there is going to be a war in the Middle East. It is as inevitable as the sunrise unless Iran stops its nuclear program. When someone says they are going to kill you and they are building the means to do so, you can't just stand by and wait for them to do it.
Knesset passes 'Norwegian Law' allowing ministers to resign their seats, remain in cabinet (Haaretz)
from the article: An inside look at the base where Iran is developing nuclear weapons