Police tossed "flash-bang" grenades into the Frank Obawa Plaza and warned protesters via a public-address system that they faced possible arrest if they didn't vacate the plaza, the San Francisco Chronicle reported.
Among those arrested was Aiyahnna Johnson, 30, of Oakland, who had been living at the camp with her 2-year-old daughter.
"We want the best for you guys, that's all," she told the officers who led her away. Her daughter wasn't with her Tuesday morning.
The Occupy movement began in New York's Wall Street district where demonstrators have been protesting corporate greed and other social ills for more than a month.
Protesters said the arrests and camp dismantling didn't mean Occupy Oakland -- a West Coast version of Occupy Wall Street -- was over. Some told the Chronicle they would return to the plaza.
"People are going to keep coming back. What are they going to do, send cops in every night and waste taxpayer dollars?" asked Gabe Meyers, a protester who had camped at the plaza but wasn't arrested Tuesday.
The police action began at 4:45 a.m. and involved officers from at least 10 law enforcement agencies, officials said. Some protesters chanted, "Cops, go home!"
The city initially waived ordinances that ban camping and allowed the occupation of the plaza. Since Thursday, however, the city has issued orders for protesters to vacate, citing concerns about fire hazards, sanitation issues, graffiti, drug use and violence.
In the nation's capital, some of the 6,500 homeless have begun to join in the Occupy D.C. protests and looking for cots in the demonstration's tent city in McPherson Square and bunks in the smaller Stop the Machine tent city in Freedom Plaza, The Washington Post reported.
Some homeless resent the occupiers, the Post said, but many say their new neighbors are doing what city leaders have tried to do for years.
"It's a good cause, and I hope they are here for months," Lynwood Baylor, 64, told the Post. Baylor sleeps in a shelter but sits on a bench in McPherson Square during the day. "This is the first time I have seen so many people here [at the park] for the same thing. There really is strength in numbers."
However, the Post said, local and federal officials are growing concerned over the tent cities.
"How do you tell the difference between homeless and protester?" asked Lt. Mike Libby of the U.S. Park Police, which is trying to determine how long the camps can remain.
The Washington demonstrations are in their fourth week.