Well, we can read what the U.S representative said the UN:

The US engaged in good faith on the text, said Deputy Permanent Representative Robert A. Wood, that would increase opportunities for hostage release and more aid to reach Gaza.

“Unfortunately, nearly all of our recommendations were ignored” leading to an “imbalanced resolution that was divorced from reality that would not move the needle forward on the ground in any concrete way. And so, we regretfully could not support it."

He said the US still could not understand why the resolution’s authors declined to include language condemning “Hamas’s horrific terrorist attack” on Israel, of 7 October.

It killed people from a range of nationalities, subjecting many to “obscene sexual violence.”

He said he had explained earlier in the day why an unconditional ceasefire would simply be “dangerous” and leave Hamas in place, able to attack again.

It was “a recipe for disaster for Israel, for Palestinians and for the entire region”.

Any ceasefire leaving Hamas in control would also deny Palestinians the chance to build something better for themselves, he added.

Moreover, the reasoning suggested in the OP that "the more the war in Gaza endures, the more there is a chance a regional war could break out" is not so obvious as it seems. Alternative view could say that if Israel stops now, the chances for WW3 would increase dramatically — it won't happen tomorrow, but probably in 2-3 years. As it would increase the likelihood that other factors would also try like Hamas to exterminate the Jews. In order to avoid war, U.S should show they are ready for war and are not afraid of it.