Israel will not be used as the rottweiler, America is closer to Iran and should do the dirty deed themselves. Either way a retalliation is certain and guaranteed against Israel regardless of who initiates the attack on Iran. So why should Israel stick its' neck out when it's the whole world especially the western nations that are at most risk from a nuclear Iran. If, and only if negotiations fail and America still refuses to do it themselves because they prefer an Israeli operation in order to distance themselves from direct involvement, will Israel have no other choice but to attack.
Yemen's Houthi rebels commit to peace plan in letter to UN chief, BBC reports (Haaretz)
from the article: In the role of the rottweiler