The owner of the building issued the citizen's arrests, charging trespassing. Five people were arrested, San Francisco police spokesman Sgt. Troy Dangerfield said.
He said the five are being taken to the police station for processing and may be cited.
The protest, organized and sponsored by Direct Action to Stop the Cuts, began Monday evening with a march from 16th and Mission streets.
The group then entered and occupied the vacant second floor of the building at 20th and Mission streets. T-Mobile occupies the first floor.
The organization, a housing and human rights advocacy group, objects to potential budget cuts that could affect the city's homeless or poor. Spokeswoman Kim Rohrbach said the funding cuts would harm housing, health, legal and mental health services.
"This was quickly organized because of the vote by the supervisors that could hold up funding," Rohrbach said of the protest.
