A citywide tactical alert was called off Monday following a day of protests in the wake of the not-guilty verdict in the George Zimmerman murder trial.
Protests lasted deep into the night and ultimately led to half a dozen arrests, including one for battery on a police officer, officials said.
About 80 protesters chanting "No justice, no peace" gathered in front of the CNN building on Sunset Boulevard in Hollywood shortly after midnight Monday, as police declared an unlawful assembly.
A police helicopter shone a light on demonstrators as more than 100 Los Angeles police officers in riot gear converged on the crowd and began making arrests and telling people to disperse. Some officers fired non-lethal rounds at the crowd.
As the protests continued Sunday, Garcetti took to Twitter and quoted Martin Luther King Jr: "Nonviolence is a powerful & just weapon .. It is a sword that heals."
He also urged residents to "exercise 1st Amendment and practice peace in City of Angels tonight."
Some marchers encouraged tourists to photograph them and join them in the demonstration. Meanwhile, street vendors went about their business, grilling hot dogs and hawking tickets for comedy shows as police helicopters hovered overhead.
Sunday evening, marchers blocked the 10 Freeway in the Mid-City area.
The California Highway Patrol said "police activity" around the 10 Freeway and Crenshaw Boulevard jammed traffic for a time.
LAPD sources said a splinter group from a larger protest walked down an onramp to the 10 Freeway and stood mostly in the eastbound lanes. Officials said portions of the 10 were closed from 6:20 p.m. to 6:44 p.m. but were then reopened.