Police Lt. William Canning of the department's robbery detail said there has been a jump in the number of robberies in the city's Glen Park, Noe Valley and Bernal Heights neighborhoods.
He said similar robberies have also occurred on the north side of the Potrero Hill neighborhood.
In many cases, one or two males between the ages of 16 and 25 wearing dark clothing approach the victim on foot and demand the victim's property, Canning said. In some cases a gun is flashed, he said.
Many robberies have occurred after dark, and most victims have been walking alone, Canning said.
Canning pointed out that robberies happen occasionally throughout the city, but that police have recorded at least 10 similar robberies in those neighborhoods since the beginning of May.
Officers from the department's Ingleside station this afternoon were preparing to distribute a notice about the robberies at the Glen Park BART station and along Church Street between 30th and Cesar Chavez streets.
The notice warns residents to avoid walking alone at night and to stay in well-lighted areas when possible.
Other tips include:
Canning also warned residents not to resist if they are robbed.
"If you are confronted, don't fight with them," he said. "You can always replace money; you can't replace your health."
"We've got officers out there looking for them," Canning said. "Hopefully nobody will get hurt and hopefully we'll catch them, with the cooperation of the community."
Anyone who notices strange activity or a suspicious vehicle is advised to contact San Francisco police at (415) 553-0123.
If calling from a cell phone during an emergency, call (415) 553-8090.