People in support and against the rezoning of the Tower District held signs and flags, shouting at each other.
During the protest, officers observed a protester kick another person as they walked by.
When officers confronted the woman, she used colorful language, then spit in an officer's face.
As they tried to detain her she ended up on the ground and received minor scrapes to her elbow.
The woman arrested was a 33-year-old from Rancho Cordova.
Her identity has not been released.