Tens of thousands of people marched in streets across the United States, staging the fourth day of protests of Donald Trump's surprise victory as president.

The protests – held in big cities such as Los Angeles, New York and Chicago as well as smaller ones, such as Worcester, Massachusetts, and Iowa City, Iowa on Saturday- were largely peaceful Saturday, although two police officers were slightly injured during protests in Indianapolis.

Protesters rallied at New York's Union Square before taking their cause up Fifth Avenue toward Trump Tower, where they were held back by police barricades.

The Republican president-elect was holed up inside his tower apartment, working with aides on the transition to the White House.

Among those railing against him was filmmaker Michael Moore, who tweeted a demand that Trump “step aside.” 

Fashion designer Noemi Abad, 30, agreed.

“I just can't have Donald Trump running this country and teaching our children racism, sexism and bigotry,” she said.

“Out of his own mouth he made this division. He needs to go – there's no place for racism in society in America.” Trump's comments – particularly a 2005 recording of him making lewd comments about women – sparked outrage during his campaign. That spilled over into demonstrations following an election that ended with half of US voters choosing the other candidate, Democrat Hillary Clinton.

Demonstrators in Indianapolis on Saturday threw rocks at police, slightly injuring two officers, said Police Chief Troy Riggs. Some protesters began chanting threats including “Kill the Police,” and officers moved in to arrest seven demonstrators.

Police briefly fired pepper balls into the crowd during the confrontation.

“We believe that we have some instigators that arrived in our city,” trying to start a riot, Riggs said.

Rowdy demonstrators marched through downtown Portland, Oregon, for the fourth night Saturday despite calls from the mayor and police chief for calm.

Several hundred people took to the streets and Portland authorities made multiple arrests after protesters threw bottles and other items at officers in riot gear and blocked streets and light rail lines. The exact number of arrests wasn't immediately available.

The gathering came after a news conference Saturday in which Mayor Charlie Hayes and Police Chief Mike Marshman urged restraint after several days of violent marches that damaged property and left one person shot.