Other protests have broken out in the San Diego, San Fransisco and San Jose areas, according to reports.
People could be heard chanting “Whose streets? Our streets” and “Not Our President”, according to Twitter users at the scene.
A demonstration also unfolded at the University of California, Davis where students blocked streets as they marched and chanted anti-Trump slogans and “You are not America, we are America,” according to Twitter posts.
Anti-racist protesters are to stage a demonstration outside the US Embassy in London following the shock election victory.
Around 120 anti-racism campaigners chanted “hey ho, Donald Trump has got to go” as they waved placards reading “No to racism. No to Trump” and depicting the president-elect as Hitler.
“He has achieved one thing though, he’s put somebody dumber than George Bush in the White House and that is himself,” one of the organisers from Say No To Racism told the crowd.
Another speaker urged Londoners to stand in solidarity with those in America campaigning against Trump’s pledge to build a wall between the US and Mexico and to ban Muslims from entering the States.
Activists accused the President-elect of having a long history of “racist outbursts” as well as his promise to build a wall between the US and Mexico.
Sabby Dhalu, co-convener of the Stand up to Racism group, said: “Donald Trump used the oldest trick in the book – he stirred up fear and racism in the context of a stagnant economy and the resulting fall in living standards – to mobilise a vote for him.
“The danger now is racists across the globe feel emboldened by Donald Trump’s victory and racism and sexism become normalised through the most powerful figure in the world.
“We call on anti-racists and all progressives to join us tonight outside the US Embassy.”
The billionaire businessman will become the 45th president of the United States after voters gambled on his pledge to “Make America Great Again”.
Speaking at a victory party in New York after rival Hillary Clinton conceded defeat, Trump urged Americans to put the election behind them.
“It is time for us to come together as one united people,” he said.
“I pledge to every citizen of our land that I will be president for all Americans.”
Taking to the stage with his family, including wife Melania, Trump promised a plan to double economic growth and invest in world-class infrastructure.
“Working together, we will begin the urgent task of rebuilding our nation and renewing the American dream.”
It would be a “beautiful thing”, he said.
The election of the outspoken businessman and TV personality, who has never held public office, shows the anger and frustration of many Americans who felt left behind by the economy and ignored by the political establishment.
Trump said: “The forgotten men and women of our country will be forgotten no longer.”
The Republican candidate sealed victory when he took key battleground states Pennsylvania and Wisconsin.
The Clinton camp initially refused to throw in the towel, but Trump told supporters shortly before 8am UK time: “I’ve just received a call from Secretary Clinton. She congratulated us – it’s about us – on our victory and I congratulated her and her family on a very, very hard-fought campaign.”
During the battle for the Oval Office, Trump had repeatedly described his rival as “crooked Hillary” and called her a “nasty woman”.
But he struck a conciliatory tone in his first appearance as president-elect, thanking the former first lady and secretary of state for her “service” to the country.
Trump sought to give reassurance to international leaders about his intentions: “I want to tell the world community that, while we will always put America’s interests first, we will deal fairly with everyone – all people and all other nations.
“We will seek common ground not hostility, partnership not conflict.”
But the markets were panicked by the Trump victory, with London’s FTSE 100 Index dropping as much as 2% on opening.
Shares also tumbled in Asia and the dollar and Mexican peso fell.