The first is that we don’t have any sort of defensive weapons between Israel and Gaza. To intercept missiles/bombs/whatever
Stuff like the Phalanx and RIM-116 at sea; or C-RAM (technically it’s the “land based phalanx system”…. But there are some critical difference in radar and the munitions it uses.
The second answer is that the US navy hasn’t been ordered to. They haven’t been ordered to because their civilian leadership is 100% okay with Israel bombing the fuck out of Gaza. Yes, that includes Biden.