Attorney General Jeff Sessions has blamed "sanctuary city" policies for crime and gang violence. "How dare you needlessly endanger the lives of our law enforcement officers?"
Several Democratic elected officials joined demonstrators and spoke to the crowd with a bullhorn.
Watch more of Sessions' remarks below.
A line of police and private security guards blocked access to the hotel. Sessions said at a news conference. The Federal Government is now suing the state over California's sanctuary state laws alleging they violate the U.S. Constitution.
The Democrat accused Sessions of lying and of trying to appease President Donald Trump.
"This is basically going to war against the state of California, the engine of the American economy", Brown said.
"California has no authority to enforce laws that obstruct or otherwise conflict with, or discriminate against, federal immigration enforcement efforts", the Justice Department said in its lawsuit, which claimed that the federal government has "undoubted, preeminent authority to regulate immigration matters". He also took particular aim at Oakland Mayor Libby Schaaf while accusing her of attempting to "score political points on the backs of officer safety". Brown wouldn't comment on that.
Attorney General Jeff Sessions attends a meeting at the White House on February 22.
The lawsuit by the Trump administration claims three of the state's laws intentionally undermine federal immigration law, according to The Associated Press. In California, a person must be convicted four times in a decade for it to be considered a felony, law enforcement sources said.
Senate Bill 54, which took effect January 1, bars state and local law enforcement officials from asking people their immigration status, prohibits them from holding migrants for pickup by ICE, and limits how much information they're allowed to provide to ICE officers. Sessions had called that bill "unconscionable".
The justices delivered a split decision, however, and declined to block the most hotly debated provision, requiring state police officers to demand the papers of anyone suspected of being in the country illegally.
There is a heavy presence of police on horses and bicycles and a helicopter overhead.
The lawsuit is the latest salvo in an escalating feud between the Trump administration and California, which has resisted the president on issues from marijuana policy to climate change and defiantly refuses to help federal agents detain and deport immigrants.
The two top officials and the state of California are named as defendants in the lawsuit filed by Justice Department lawyers on behalf of the United States.
"I encouraged people to not panic but to know their rights, to know their responsibilities and to know about the unique resources that are available in this community". "What they've done is force my officers to arrest risky criminals on their turf, in their homes and their places of business rather than arresting them in the safety and security of a county jail, its ridiculous".