The march of several dozen protesters arrived at the campaign headquarters on Telegraph Avenue about an hour later, and seven protesters entered the building.
Some of the seven protesters sitting inside wore t-shirts reading "Iraq Veterans Against the War," including Scott Olsen, an Iraq War veteran seriously injured by a police projectile during an Occupy Oakland protest on Oct. 25.
Police arrived shortly after the seven entered the building, later locking the doors and leaving the larger crowd of protesters outside.
Three veterans and four other activists talked with a police negotiator as a dozen other police officers stood nearby, but the activists refused to leave.
Police then moved in to arrest the group at around 9 p.m.
The campaign headquarters, located at Telegraph Avenue and 16th Street, had boarded windows when the march arrived. During a previous demonstration on Aug. 3, protesters smashed windows of the building while protesting at Oakland's monthly "Art Murmur" event.
The protesters said in a statement that they were demanding that President Obama apologize for statements they said he made regarding Manning's guilt, that the president ensures soldiers are free from pre-trial punishment, alleging that Manning was held in long periods of isolation, and that Manning be pardoned.
Shortly after the six were arrested, demonstrators standing outside of campaign headquarters marched toward Oakland Police headquarters.
Obama campaign headquarters was closed Thursday night after the arrests and there was no word on the charges the protesters face.