Because Isreal is a leading military power in the Middle East. They are Western in most of their views and the US can deal with them. You can’t say the same about any of the other Middle Eastern nations.
Israel is coming down hard on Gaza and Hamas to make an example of them. They are going to send that strip back to the Stone Age. This operation is a statement, “this is what happens when you fuck with us. “
No other Middle Eastern powers give a shit about Gaza. They make noises to appease their populations. But no other Nation has offered direct military assistance or action.
In short it would be stupid to drop Israel as an ally over this.