The object that caused the concern was found in the 600 block of Parnassus Avenue. The fire department was notified of the incident at 7:46 a.m.
The San Francisco Police Department's bomb squad was called in, and Parnasssus Avenue was shut down.
A nearby UCSF childcare facility was evacuated, university spokeswoman Elizabeth Fernandez said.
Police gave the all-clear at about 10 a.m., Fernandez said.
San Francisco Municipal Railway's 6 and 43 lines were rerouted while the street closure was in effect, Muni spokesman Paul Rose said.