President Trump has offered mixed messages since Israel launched its military campaign against Iran last week, vacillating from a hands-off approach to embracing diplomacy to at times suggesting that he was weighing further U.S. involvement.

The contradictory comments have left a trail of confusion as Israelis, Iranians, and the broader Middle East try to understand whether the biggest conflict between Israel and Iran in history would escalate further and whether Mr. Trump, long opposed to foreign wars, would plunge the United States into one.

“It’s very puzzling,” said Shira Efron, director of research at Israel Policy Forum, a New York-based research group. “You’re seeing him say one thing and then another.”

On Friday, the first day of the war, Mr. Trump initially called Israel’s attacks “excellent” and “very successful,” but he also said that he believed a diplomatic solution between Israel and Iran was possible.

“There has already been great death and destruction, but there is still time to make this slaughter, with the next already planned attacks being even more brutal, come to an end,” the president said. “Iran must make a deal, before there is nothing left.”

The following day, Mr. Trump recounted a call with President Vladimir V. Putin of Russia, saying that both he and Mr. Putin said the battle between Israel and Iran should end. And on Sunday, he reinforced his stated position by saying Israel and Iran should make a deal.