I gotta agree. We have to protect our interests and when any other country, I don't care how cozy of a relationship we have, is trying to hurt US interests, I say we have to fight back. Withholding some financial aid seems like a great start. Since they seem to have enough money to spy on us, it shouldn't hurt too much.
And I would say the same if it was Canada, Spain, Great Britian, or Egypt.
We bend over backwards to keep Israel safe and then they feel the need to spy on us? With allies like that, who needs enemies?