The robbery was reported at about 9:50 p.m. near Ellis and Hyde streets. The victim was approached by someone who grabbed the phone from his pocket, according to police.
The victim struggled to take the phone back but was overpowered by the suspect, who ran away with it, police said. The victim was not injured in the robbery.
The suspect, a white man in his 40s or 50s, has not been found.
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.