The attack happened at about 10:45 p.m. at an office in the 500 block of Sutter Street.
Three suspects -- a woman and two men in their early to mid 30s -- approached the 29-year-old victim and beat and bound him, according to police.
The suspects then took three computers from his office and fled. They had not been found as of this morning, police said.
The victim was taken to San Francisco General Hospital to be treated for his injuries, which are not considered life-threatening.
Anyone with information about the case is encouraged to call the Police Department's anonymous tip line at (415) 575-4444 or send a tip by text message to TIP411.