The stop in Los Angeles came without the usual courtesy notice.

Gov. Gavin Newsom was in Southern California on Thursday morning to celebrate the debut of two giant pandas at the San Diego Zoo. But hours later, he emerged 127 miles up the freeway, driving home his message of the moment: Famously tolerant California isn’t tolerating homeless encampments anymore.

Since July 25, when the governor urged California cities to dismantle the street camps that have come to define the state’s homelessness crisis, leaders in Los Angeles have been particularly resistant to Mr. Newsom, making clear that they plan to deal with the issue in their own way and on their own timetable.

On Thursday, Mr. Newsom, in sunglasses, jeans and a black ball cap, visited two homeless encampments on their turf without directly informing city or county leaders. The only advance notice seemed to be state placards that warned people days ago they were facing citation or arrest if they continued to stay there.

“People are done. If we don’t deal with this, we don’t deserve to be in office,” Mr. Newsom said, tearing into a rancid, garbage-strewn campsite on state property under Interstate 10 in Los Angeles, alongside a crew of state workers in orange vests.

His mission, he said, was part public service, part political flex. The governor said that he particularly wanted more “urgency” from the leaders of Los Angeles County, home to nearly 10 million Californians, where unsheltered homelessness decreased last year at about half the rate as it did in the City of Los Angeles, its largest jurisdiction.

“We need partners, not sparring partners,” Mr. Newsom said. “If we can’t move Los Angeles County, we’re not going to move the state.”