WASHINGTON — The guests, in their witches’ hats and Princess Leia buns, were not too adorable to hear some difficult truths from their commander in chief.

“I cannot believe the media produced such beautiful children,” President Trump marveled, surrounded in the Oval Office by the Halloween-costumed offspring of White House reporters. “How the media did this, I don’t know.”

The children stared vacantly. The candy had not yet arrived.

For some 180 seconds on Friday, these visitors inspired a quintessential Trump performance — part executive gripe session, part grandfatherly charm, part open-mic night for the under-12 set.

But one throughline was clear: Mr. Trump regretted to inform his new friends that their parents, while surely nice enough at home, were not to be trusted.