The nanny had two young children with her and this appears to be one of many incidents involving harasssment or intimidation following the election.
This was called in as a hate crime, but police have not yet charged the person they believe is responsible because they're getting his mental health checked out.
The nanny suffered scratches on her arm, but she is OK.
A woman first reported the alarming encounter on the social network site Nextdoor.
She wrote that her nanny was attacked while caring for her two children. Part of it said: A "man in all black came from behind, pulled her hair and neck and told her "no Latinos here" in Spanish.
This happened at one of San Francisco's most popular and picturesque parks - Great Meadow Park at Fort Mason. "The woman suffered some scratches I understand and was certainly shaken by the experiences," National Park Service spokesperson Nathan Sargent said.
Sargent says a jogger helped the nanny and called police.
Officers did detain a man who fit the suspect description. "This is an individual with some mental health issues. He was transported to San Francisco General Hospital and he is there now going under a psychiatric evaluation," Sargent said.
This is just one of several reported hate crimes across the country many feel have been fueled by the presidential election.
At UC Berkeley, a couple of men allegedly threatened and taunted a Muslim student. And in San Jose, a student told ABC7 News someone pulled off her head scarf last week.
Mayor Ed Lee on nanny attack: "It gives me great grief to hear that this is happening." #abc7now— ElissaABC7 (@ElissaABC7) November 15, 2016
San Francisco Mayor Ed Lee says he's taking all threats seriously, including the attack on the nanny. "It gives me great grief to hear that his happening just like any of the incidences that reflect a higher level of discrimination or bigotry," Lee said.
The mayor is working with police and the city attorney, urging calmness in the city.