When Israel has been threatened in the past, the outside world (friendly and unfriendly) has urged restraint and to not to take direct action. Invariably, in such cases, the outside world has been wrong. Had Israel taken such advice in the past, it probably would not exist today.
What if Israel acknowledged its own collection of nuclear weapons and announced a willingness to get rid of the entire arsenal in exchange for an Iranian promise to stop pursuing the bomb? Worst case, Iran refuses the offer, continues building its nukes, and we're back to square one. Either way, Israel has offered peace to its most dangerous enemy.