DUBAI—Iran has been urgently signaling that it seeks an end to hostilities and resumption of talks over its nuclear programs, sending messages to Israel and the U.S. via Arab intermediaries, Middle Eastern and European officials said.

Iran has told mediators Qatar and Oman that it is not open to negotiating a ceasefire while it is under Israeli attack, an official briefed on the communications told Reuters on Sunday, as the two foes launched fresh attacks and raised fears of a wider conflict.