The owner of a Los Angeles bar has apologized after an aggressive faceoff — partially recorded in viral videos — between a right-wing men’s group and leftist protesters who showed up to confront them.

About 20 members of the Proud Boys — a “Western chauvinist” organization that advertises chapters across North America and Britain — gathered Saturday night at the Griffin, a low-key bar across the street from a carwash in northeast Los Angeles.

The men were quickly spotted because of their matching outfits: black Fred Perry polo shirts, striped yellow on the fringes, usually complemented with a “Make America Great Again” cap. This is the uniform of the Proud Boys, which the Southern Poverty Law Center calls a violent hate group, though it describes itself as merely a defender of traditional male and “Western” values.

The group claims to initiate new members through rites of fraternal violence — similar to “jumping in” ceremonies used by certain gangs. Members are promoted through acts of fealty — namely tattooing themselves and engaging in “major conflict,” including fights, against the Proud Boys’ culture enemies on the left.

Prominent among those cultural enemies is the Democratic Socialists of America, whose Los Angeles chapter happened to be out Saturday celebrating a member’s recent upset victory in a Democratic congressional primary, not far from the Proud Boys meetup.

“I got a text from a friend: ‘Hey, I heard there’s a Proud Boys meeting at the Griffin,’ ” Democratic Socialist member Josh Androsky recalled. “I texted another friend.”

Before long Androsky and members of other like-minded groups were on Twitter and Facebook, calling anyone available to get to the Griffin and shame the men he called “Nazis.”

“Nazis aren’t allowed to have fun in Los Angeles,” Androsky told The Washington Post. He recognized that the Proud Boys deny any affiliation with white supremacy or the alt-right and was not moved. “They want to make a distinction they’re not from Germany in the 1940s, but we have a handy word to call right-wing fascist hate groups. It’s ‘Nazi.’ ”

So Androsky and his girlfriend drove over to the Griffin in his electric car. When he arrived around 9 p.m., he said, about eight people were in his group of democratic socialists and allied groups, compared with nearly two dozen Proud Boys in the smoking area.

“They had closer to four than eight, but we can call it six,” an unnamed spokesman for the Proud Boys wrote to The Post on Twitter. He agreed there were 20 in his own group.

“We were there having beers with friends,” he wrote. “They came to the bar to start a problem. They did.”

What began the problem depends on whom you ask.

“When we first entered the bar, they were keeping to themselves,” Androsky said. “We quietly pulled staff members aside and said: ‘Hey, we just want to let you guys know something’s going on. . . . They’re wearing uniforms. Google them.’ ”

“They just ignored us completely,” he said.

Video from the bar, published by L.A. Taco, appears to show a bar manager arguing with Androsky as he tries to convince staffers that the Proud Boys were extremists.

“Why do they have black guys and Mexican guys with them?” the employee says. “Why am I defending them? I’m a liberal!”

“Stop defending them!” Androsky says.

In an apologetic Facebook post Sunday, the unnamed owner of the Griffin wrote that the bar had been unprepared to be “overrun by a hate group” and that staffers had been advised not to confront the Proud Boys, in the hope they would “get bored and go away.”

“We are generally a pretty mellow and peaceful bar with no real security,” the owner wrote. “I foolishly thought this was the best way to ensure they’d leave without putting my staff in danger.”

After more than half an hour, Androsky said, the Proud Boys came into the main bar area and started harassing random patrons.

“I saw them create a half circle, blocking in guys,” he said. “It’s not hard to guess what the dispute was about. When you see a bunch of neo-Nazis and people of color, I think it’s probably about the fact that there are neo-Nazis in the bar.”

In Androsky’s version of events, he intentionally antagonized the Proud Boys to draw their attention away from the nonwhite patrons they were bothering.

In the Proud Boy spokesman’s account, the men were just drinking and were accosted by Androsky’s group: “Josh grabbed a hat from one of our guys. It was returned soon after.”

However the fracas started, frenetic video clips show people jostling each other under a glowing exit sign, their shouts and curses wildly out of sync with the ambient music.

“Hey! Hey! Hey!”

“Let me out of here!”

Androsky said the Proud Boys surrounded him. One man shoved his girlfriend when she tried to intervene, he said, and in the ensuing scuffle someone knocked his glasses off.

“His girlfriend shoved some of our guys and she was pushed,” the Proud Boys spokesman wrote, contradicting Androsky’s account.

They agreed that bar staffers soon separated the groups, which Androsky said is when the chanting started.

“No Proud Boys, no KKK, no fascist USA” — over and over. Androsky said several bar patrons had by then sided with his small group, joining in the chorus.

“Fascist pigs!” someone yells at the Proud Boys in one of the videos. “Yeah, squeal! Squeal and cluck your hoofs together . . . hogs. All of you — you’re all swine, sweaty swine.”

The Proud Boys spokesman told The Post he had heard all this before. “They call us all of that,” he wrote. “Anyone who supports the president is a Nazi to them.”

A manager finally orders both groups out the door. Androsky said the Proud Boys exited first.

“What about the Nazis outside?” someone in the video protests when it is his turn to leave. “Are we safe to leave with the Nazis outside?”

“I don’t know if you’re safe outside,” replies the manager. “But we’re closed in here. I’m sorry.”

The argument was cut short with an announcement that two police officers had arrived, after which both groups moved to the sidewalk.

While no one was arrested or injured during the confrontation, a final video shows a Proud Boy — complete with polo and red hat — arguing about world history.

“Yeah, and the Irish people were slaves, just like the–” he said, before breaking into expletives and indistinguishable syllables. “Wah, wah, wah.”

A woman finally pried the man away from the camera. “Let’s go.”

Androsky said he watched two police officers escort the entire group around the corner and out of sight, where he heard they were refused entry into other bars.

They will not be welcome back in the Griffin, the owner said, after the bar’s Yelp reviews and Facebook page were spammed with angry comments as videos of the encounter spread.

From one purported review on Yelp: “Came for the roasting of Nazi sympathizers, stayed for the pictures of awful looking dishes.”

It was, in a way, the inverse of what happened to the Red Hen — a tiny rural Virginia restaurant that was assailed by conservatives after its owner asked White House press secretary Sarah Huckabee Sanders to leave.

The Griffin’s owner attempted to explain himself in a long Facebook post on Sunday afternoon.

“Neither I nor my business partner support any Nazi or white supremacist groups and this is not a Nazi bar,” he wrote. “It’s my bar and I’m ultimately responsible for what happened last night and I feel terrible and actually sick to my stomach. All the mistakes that were made were due to lack of communication and inexperience. We are not a bar that in any way supports hate groups and any staff that does will be dealt with.”

In a follow-up post, the owner said the Griffin would remain closed Sunday evening and post anti-hate signs to keep Proud Boys away in the future.

This article has been updated with more comments from the Proud Boys spokesman.

An earlier version of this article incorrectly characterized Androsky’s version of the scuffle. He said a Proud Boy shoved his girlfriend; not him.