Israelis turned out in multitudes on Saturday to rally for the release of the hostages in Gaza, and they left no doubt about whom they credited for the captives’ imminent return.

“Thank you, Trump! Thank you, Trump!” the crowds filling the Tel Aviv plaza known as Hostages Square chanted in English as Steve Witkoff, President Trump’s Middle East envoy, spoke from the podium, flanked by Ivanka Trump and Jared Kushner, Mr. Trump’s daughter and son-in-law.

Mr. Witkoff spoke emotionally about the families of the hostages, saying their courage had affected him in ways he had never been before.

“I dreamed of this night,” he said, alluding to the cease-fire deal between Israel and Hamas that he and Mr. Kushner helped negotiate, and that provides for the release of the hostages in exchange for Palestinian prisoners by Monday.

“I only wish the president was here,” Mr. Witkoff added in his address, which was broadcast live on Israeli television. “He would love this.”

Israelis have rallied in the thousands on Saturday nights for most of the past two years, demanding that all the captives still held in Gaza be brought back “Now!”