Any attack on Israel will be considered an attack on the United States and will be treated accordingly. If the state which attacks Israel is already in a state of hostility with the United States, we will increase our military campaign an order of magnitude.
On the other hand, anyone who wishes to negotiate with Israel in good faith on valid issues affecting their respective states can count on the United States to help. We believe in peaceful negotiation and will do everything we can to support the same.
That's what I'd do.
It's probably too simple, though.
Shalom.