By Noel Randewich and Dan Levine

OAKLAND, Calif (Reuters) - Police moved in to clear anti-Wall Street protesters from a downtown Oakland plaza on Monday, arresting 32 people but avoiding clashes that marked a previous attempt to shut down the Occupy Oakland camp.

Several dozen officers dressed in riot gear and carrying batons descended on the square shortly after dawn but took a less aggressive approach than in a similar move three weeks ago, and were met with less resistance from demonstrators.

The previous move had sparked clashes between protesters and police that turned into one of the most violent episodes since the anti-Wall Street movement began in New York in September, targeting a financial system protesters believe most benefits corporations and the wealthy.

Former Marine Scott Olsen was critically injured during that altercation, giving impetus to protests nationwide. Olsen, 24, was released from the hospital last week and has called for peaceful demonstrations.

Monday's police action saw officers sometimes smiling and talking with protesters as they took down about 100 tents as a helicopter overhead illuminated the area. A separate line of officers kept a chanting crowd from entering the camp.

By rush hour on Monday, Frank Ogawa Plaza was fenced off as police and a handful of protesters lingered at the edges, the latter singing songs at a blocked-off intersection.

"We had to bring the camps to an end before more people got hurt," Mayor Jean Quan told a news conference after the action. City officials said they hoped to reopen the central plaza to demonstrators by 6 p.m. but would not allow camping.

City officials said there were no injuries to citizens or officers and that Frank Ogawa Plaza would reopen for peaceful demonstrations, but that protesters would no longer be allowed to camp there.

'I'M MOVING ON'

Still, the move was not without conflict and prompted the resignation of a top adviser to Quan, who has come under heavy criticism for her handling of the Occupy movement in her city.

"He's moving on, I'm moving on," Quan said of the decision by civil rights attorney Dan Siegel to resign shortly before the raid.

Before the camp was completely cleared a crowd of protest supporters chanted "Shame on you!" and one protester, Joanne Warwick, said the police action was disturbing.

"Here we are after five weeks and we can't work this out," she said.

Occupy Oakland organizers said they would reconvene on Monday afternoon at the main downtown library.

Oakland is one of several cities where authorities have moved in recent days to shut down Occupy camps, saying they have become sources of rising crime.

The weekend saw police clearing operations in Portland, Oregon; Salt Lake City, Utah; and Denver, Colorado, as well as threats of action in other cities if protesters did not clear out on their own.

In St. Louis, where 27 anti-Wall Street protesters were arrested on Saturday, attorneys for members of Occupy St. Louis planned to take their battle to regain their downtown campsite to federal court on Tuesday.

They were seeking an injunction that would allow an overnight presence in Kiener Plaza, the downtown city park near the Gateway Arch where the protests against economic inequality maintained a camp for six weeks.

Meanwhile in New York, protesters said they would seek to shut-down Wall Street on Thursday by holding a street carnival to mark the two-month anniversary of their campaign.

Organizers acknowledged that the move could be the group's most provocative yet and could lead to mass arrests and further strain relations with city authorities.

(Additional reporting by Jim Christie, Peter Henderson, Mary Slosson, Dan Whitcomb, Bruce Olson and Chris Francescani; Writing by Dan Whitcomb; Editing by Jerry Norton and Cynthia Johnston)