Police arrested about 300 "Occupy Oakland" protesters on Saturday, following a chaotic day of clashes.
Protesters broke into City Hall -- closed for the weekend -- where they burned American flags and damaged property, The Associated Press reported.
"This is not a situation where we had a 1,000 peaceful people and a few violent people," said Oakland Mayor Jean Quan.
"If you look at what's happening today in terms of destroying property, throwing at and charging the police, it's almost like they are begging for attention and hoping that the police will make an error," she said.
City Administrator Deanna Santanta said the protesters followed through on their stated goals to "provoke officers and engage in illegal activity."
Late Saturday, demonstrators disrupted traffic as they marched from City Hall to the vacant Henry Kaiser Convention Center, which they had threatened to take over.
Just before 3:00 p.m., some of the "occupiers" began tearing down the perimeter fencing and "destroying construction equipment," AP reported.
Protesters threw rocks, bottles, burning flares and other objects at police, who responded with smoke and tear gas.
The group referred to the protests as "constitutionally protected civil disobedience."
"Occupy Oakland's building occupation, an act of constitutionally protected civil disobedience, was disrupted by a brutal police response today," the group reported by email.
Oakland Councilman Ignacio De La Fuente called the day's events "domestic terrorism," saying it could not be allowed to continue.
Interim Police Chief Howard Jordan said he stayed in "close contact" with a court-appointed monitor throughout the protests.
Mayor Quan said police response had been "very measured, noting that "a majority of protesters who were charging the police were clearly not being peaceful."
"If the demonstrators think that because we are working more closely with the monitor now that we won't do what we have to do to uphold the law and try keep people safe in this city, they're wrong," the mayor said.
The Occupy Oakland movement is an offshoot of the Occupy Wall Street movement, which began last fall in New York City.