WASHINGTON—After moving to the precipice of military action against Iran, President Trump finds himself caught between negotiations that show few signs of yielding a nuclear deal and a war he is reluctant to join.

Hours of talks aimed at de-escalating fighting between Israel and Iran failed to produce a diplomatic breakthrough as the war entered its second week with a fresh round of strikes between the two adversaries.

Trump said he was waiting to see “whether or not people come to their senses.”