takah: Actually American diplomats in the embassy very much *will* intervene if you’re a U.S. Citizen and request their assistance. They are legally obligated to take your case up with the Israeli authorities irregardless whether or not the American citizen holds dual citizenship with any other country. As far as the U.S. Consulate is concerned you hold a U.S. passport and that is all they care about and they will intervene on your behalf.
It is certainly worthwhile getting the American diplomats (or the diplomats of your country) involved on your behalf. The Israelis are quesy about messing with America. Just the fact that America is coming to her citizens defense will possibly cause the Israelis to back off. I know of such a case where an American in the IDF was discharged only after getting the U.S. Embassy involved.
And especially considering if it is a case of a born-and-bred American citizen who lived in America and who is only a technical Israeli by virtue of one or both of his parents Israeli passport, America will certainly come to bat on his behalf.