In California, where memory of the Rodney King riots two decades ago loomed heavily over the city's demonstrations, protesters clashed with police and several arrests were made.
While Los Angeles protests remained largely peaceful, police said, several "splinter groups" have been more aggressive and the LAPD called a citywide tactical alert.
Officers declared unlawful assembly shortly after midnight Monday after about 80 people gathered in front of the CNN building in Hollywood, chanting "No justice, no peace" and carrying signs.
At Washington Boulevard and 10th Avenue, demonstrators threw rocks and D-cell batteries at cops.
Police made at least seven arrests and dispersed the crowd, some even firing rubber bullets and bean bags.
No arrests were made, and none of the protesters was hurt, when a crowd blocked the 10 Freeway at Crenshaw Boulevard, jamming traffic for more than 20 minutes as they marched down the highway.
In Oakland, protestors vandalized businesses downtown, while police in riot gear watched over San Francisco demonstrations but made no arrests.
Oakland Mayor Jean Quan said the protestor's actions "dishonored the memory" of Trayvon Martin by their actions.
“Oakland is a community that grapples with many of these issues,” Quan said. “I know many of us are living with hard emotions as we continue working toward solutions in the wake of the verdict.”
Marchers spray-painted anti-police slogans on buildings and businesses, lit garbage cans on fire and smashed windows, said police spokeswoman Johnna Watson, but no arrests were made.