He applauded officers' restraint, saying it forestalled greater violence.
The number of arrests was revised down from 14, previously suggested by the police.
Sunday's events follows rowdy protests in San Francisco Saturday.
House Minority Leader Nancy Pelosi, did her part by labeling it a "white supremacist rally at Crissy Field" - there's no indication Pelosi was asked to support her statement with facts.More news: Manchester United vs. Leicester City 2017 live stream
Police in riot gear lined up Saturday along a fence erected at the park after the right-wing group Patriot Prayer said it planned to hold a news conference at the location.
"It's important for people to show up and make it unacceptable for right-wing white supremacists to spew hate and incite violence", rally organizer Jeff Conant, 50, of Berkeley, told SF Gate.
More than a dozen people were arrested. Once anarchists arrived, it was clear there would not be dueling protests between left and right so he ordered his officers out of the park and allowed the anarchists to march in. Peaceful anti-Trump protesters expressed discontent with antifa; one woman told the LA Times that she anxious the march would be tied to violence, while another man said, "We need to get antifa out of here".
"What you're seeing is a ideal example of the systematic oppression of right-wing thought and ideology", Chapman said on Facebook Live.More news: Tillerson distances himself from Trump's Charlottesville response
Gibson of Patriot Prayer canceled his Saturday event, citing safety.
The No to Marxism in America rally was organized by Amber Cummings, a transgender Trump supporter of President Trump who had previously denied allegations that the No to Marxism event was a white-supremacy gathering.
According to local news sources, at least 10 people were arrested for violating rules against covering the face or carrying banned items. "Do not!" said Tur-Ha Ak of the Anti-Police Terror Project. "Our nation is deeply divided, but Berkeley will forge onward to protect immigrants, people of color and others who are marginalized, and to continue to peacefully stand up for justice", the mayor said. In addition to Berkeley police, members of the Alameda County Sheriff's Department, Alameda police, and the California Highway Patrol are on hand.
Campus officials will add more police to the event than were present for the scheduled appearance of another conservative, Milo Yiannopoulos, Christ said.More news: Ronda Rousey and Travis Browne to Wednesday on Saturday
On Hayes Street near Alamo Square park, people handed out free cups of water, pastries and flowers to fellow demonstrators, in San Francisco-style. If we don't stand against the attack on free speech in Berkeley, then it won't be long before it's in my neighborhood and I have to be anxious about my political beliefs.