The robbery was reported at 6:40 p.m. at a business in the 1800 block of Market Street.
The suspects, described as about 20 years old, walked into the store to buy cigarettes but the 41-year-old employee refused because the suspects looked young, according to police.
One of the suspects then punched the man in the throat and grabbed various tobacco products, and the trio ran out of the store, police said. The victim suffered minor injuries in the attack but declined transport to a hospital.
The three suspects had not been found as of this morning. Anyone with information about the robbery is encouraged to call the Police Department's anonymous tip line at (415) 575-4444 or send a tip by text message to TIP411.