President Trump hosted a teenage lifeguard and a boy he had saved at the White House on Monday, as he snapped at a CNN reporter and took questions on a variety of matters.

The Oval Office event was held to commend the lifeguard, Ryder Williams, who was widely lauded for dragging Nathaniel Rai, 10, from crashing waves at a beach in Santa Cruz last month in a rescue that went viral. But during the meeting, as his guests looked on, Mr. Trump criticized the CNN White House reporter Kristen Holmes.

Ms. Holmes is heard off camera trying to ask a question about North Korea as Mr. Trump demands that she “be quiet.”

It is not uncommon for Mr. Trump to take wide-ranging questions from the news media when he is hosting guests at the White House. He has frequently singled out women and journalists of color during such exchanges.

Earlier, Ms. Holmes asked Mr. Trump about a recent comment made by Senator Jon Ossoff, Democrat of Georgia, referring to Mr. Trump’s travel with an aide, Natalie Harp. Mr. Trump sidestepped the question in the Oval Office. The White House later called the question “disgusting and inhumane” in a post on social media, and said her children would one day be embarrassed.

CNN defended Ms. Holmes in a statement that said personal attacks were beneath the office of the president and “inconsistent with the principles of a free press.”

During the meeting, Mr. Trump praised Mr. Williams’s actions as well as those of the lifeguards who had helped train him and joked that he might not have saved the boy if he had been the lifeguard on duty.

“He’s a real hero. I don’t know if I’d do it. I wouldn’t, probably,” Mr. Trump said of the rescue.

“You’re lucky I wasn’t on the service that day,” he said, speaking to Nathaniel.

During Ms. Holmes’ question about North Korea, Mr. Trump turned to Nathaniel and said the boy understood that Ms. Holmes was being “disrespectful.”