He waved his hands horizontally.
“Mmm, don’t answer,” he decided, as a Leia and a Batman looked on quizzically. “That can only get me in trouble, that question. No. You have wonderful parents, right?”
There was more: “So, how does the press treat you? I’ll bet you get treated better by the press than anybody in the world, right? Huh? I think so. Hi, sweetheart.”
And some for the parents: “Well, congratulations, folks,” he said, turning to the journalists and gesturing toward the children. “You did a good job. You did a good job. Here, you did a good job.”
He pointed to himself. “I wouldn’t say you did very well here. But really, beautiful children.”
The group did not leave empty-handed. As Mr. Trump riffed, the White House press secretary, Sarah Huckabee Sanders, delivered him a collection of sweets to distribute.
“What is this? Ooohhh,” Mr. Trump said. “Well, I don’t think they want any gifts or candy, right? You ready? So this is from the White House, look. See what that says?”
“Ooh, they’re Hershey’s Kisses,” a girl observed.
“Who likes this?” the president asked. “And you have no weight problems. That’s the good news, right?”
The joke did not kill in this room.
Other efforts to connect were more successful. When a younger child, unnerved by the cameras, appeared on the verge of tears, the president reached over, hoping to console her.
“Are you crying? Come here, sweetheart,” he said.
“She’s Japanese,” another child said.
“She’s Japanese!” Mr. Trump replied, flashing a quick smile. “Beautiful. She’s Japanese. I’m going to be in Japan. In two weeks, I’ll be in Japan.”
“I know,” another girl said, nodding in a green-trimmed witch’s hat.
Some outfits seemed to pique the president’s interest more than others.
On a Darth Vader mask: “Scary outfit,” he said twice.
On the girl with purple hair: “What color is that? Purple?”
With this, Ms. Sanders indicated that it was time to wrap up. She and Mr. Trump thanked everyone.
“They can stay,” Mr. Trump said of the children, with a smirk and a sweep of his hand. “The parents, maybe not so much.”