President Volodymyr Zelensky of Ukraine reiterated in an interview that aired on Sunday that his country would “never” accept a peace deal struck by the United States and Russia if Ukraine did not have a seat at the negotiating table.

In an interview on NBC’s “Meet the Press,” Mr. Zelensky sought to avoid criticisms of President Trump and instead praised his strength. He said he had told Mr. Trump during a phone call, shortly after Mr. Trump and President Vladimir V. Putin of Russia spoke for 90 minutes last week, that Mr. Putin is untrustworthy and feared Mr. Trump.

Mr. Zelensky said he believed that Mr. Putin was “scared” of Mr. Trump, playing toward Mr. Trump’s desire to be seen as strong and the hope that the U.S. president could push Mr. Putin toward a deal he might not otherwise favor.

“I said that he is a liar,” Mr. Zelensky said he told Mr. Trump of Mr. Putin. “And he said, ‘I think my feeling is that he’s ready for these negotiations.’”

Mr. Zelensky added: “But I think he’s really a little bit scared about President Trump. And I think the president has this chance, and he’s strong. And I think that really he can push Putin to peace negotiations.”

Mr. Zelensky’s interview came as three top foreign policy aides in the Trump administration — Marco Rubio, the secretary of state; Mike Waltz, the national security adviser; and Steve Witkoff, the Middle East envoy who also works on Ukraine-Russia issues — were expected to meet with Russian officials in Saudi Arabia in the coming days to discuss a path to ending the war. It would be the first substantial talks between the two countries on the conflict, three years after Russia’s full-scale invasion.