One thing that will certainly crush the youth rebellion in Iran is if the United States attacks Iran. Bomb Iranian nuclear facilities and all of the patriotism that is being invested in opposing their stolen election will be refocused against the foreign invaders.
The only exception is if the Revolutionary Guard begins the mass slaughter of Iranians. Then, and only then, can the United States intervene. Not a few hundred deaths, only tens of thousands being killed can justify American intervention.
At no point can Israel act. Any military action by Israel can only insure that Ahmadinejad will be given total control of Iran and unconditional support.