Donald Trump has accused the media of “inciting” protests against his election victory as demonstrations continue days after the shock result.

Thousands of people have taken to the streets in cities including New York, Chicago and Portland for two consecutive nights, with some rallies seeing clashes with armed police and arrests.

The President-elect took to Twitter to respond on Thursday night.

He said: “Just had a very open and successful presidential election. Now professional protesters, incited by the media, are protesting. Very unfair!”

Protesters gather in Pioneer Courthouse Square in Portland, the third night of protests over the results of the presidential election, on 10 November 2016. (AP)

As polls predicted an emphatic victory for Hillary Clinton in the run-up to the vote, Mr Trump repeatedly suggested he would contest the election result and accused the system of being “rigged”.

US President Barack Obama said the Republican candidate was “undermining democracy” with comments questioning its legitimacy “without a shred of evidence”.

Mr Trump previously called on Americans to “march on Washington” Mr Obama’s victory four years ago, calling for a revolution against the electoral system.

“We can't let this happen,” read a tweet posted on 7 November 2012. “We should march on Washington and stop this travesty. Our nation is totally divided!”

But he has not repeated the sentiment following his own election victory, when the Electoral College system he once called a “disaster for democracy” allowed him to beat Ms Clinton despite her winning more votes.

A second night of protests against the shock result saw violence break out in the city of Portland, Oregon, when police responded to riots with pepper spray and stun grenades.

Hundreds of people marched through the streets, chanting: “We reject the President-elect!” before a small groups started to vandalise shop windows, set fire to rubbish bins, smash car windows and set off firecrackers.

As clashes continued into the early hours of Friday morning, police warned that blocking motorways and roads amounted to unlawful assembly and would be met with force, ordering crowds to disperse.

“Police advising crowd there are gas and flares being prepared by protestors,” a statement said, adding that projectiles were being thrown at officers.

“After several orders to disperse, police have used less lethal munitions to effect arrests and move the crowd.”

Anarchist groups were being blamed for fuelling the violence, which concentrated on the upmarket Pearl district and its designer shops. A local television crew's camera was hit by a man who was then chased off by Black Lives Matter protesters, journalists said.

At least 26 people have been arrested in connection with the disorder.

In Denver, Colorado, protesters briefly shut down the Interstate 25 motorway, while in San Francisco students marched through the city centre chanting: “not my President” and holding up signs demanding Mr Trump be removed from office.

They waved LGBT rainbow banners and Mexican flags, as bystanders in the mostly Democratic city high-fived the marchers from the sidelines.

“As a white, queer person, we need unity with people of colour, we need to stand up,” said Claire Bye, a 15-year-old pupil. “I'm fighting for my rights as an LGBTQ person. I'm fighting for the rights of brown people, black people, Muslim people.”

The Independent was at a rally in New York City, where a large group of demonstrators once again gathered outside Trump Tower on Fifth Avenue, making speeches, chanting and waving placards bearing anti-Trump messages.

President Trump protests Show all 20 1 /20 President Trump protests President Trump protests Patrons hold a sign as people march by while protesting the election of Republican Donald Trump as the president of the United States in downtown Los Angeles, California Reuters President Trump protests Demonstrators rally following the election of Republican Donald Trump as President of the United States, in Oakland, California Reuters President Trump protests Demonstrators march following the election of Donald Trump as President of the United States Reuters President Trump protests Thousands of protesters rallied across the United States expressing shock and anger over Donald Trump's election, vowing to oppose divisive views they say helped the Republican billionaire win the presidency AFP/Getty Images President Trump protests Demonstrators protest outside the Chicago Theatre in Chicago, Illinois Getty President Trump protests A police officer aims a launcher after demonstrators threw projectiles toward a line of officers during a demonstration in Oakland, California Reuters President Trump protests An officer examines a vandalized police vehicle as demonstrators riot in Oakland, California Reuters President Trump protests Demonstrators take over the Hollywood 101 Freeway just north of Los Angeles City Hall in protest against the election of Republican Donald Trump as President of the United States Reuters President Trump protests A woman holds up a sign reading 'Trump you are an Idiot' as demonstrators gather during a protest against President-elect Donald Trump outside the City Hall building in Los Angeles, California EPA President Trump protests A masked demonstrator gestures toward a police line during a demonstration in Oakland, California Reuters President Trump protests Demonstrators protest against the election of Republican Donald Trump as President of the United States, near the Trump International Hotel & Tower in Las Vegas, Nevada Reuters President Trump protests Musician Lagy Gaga stages a protest against Republican presidential nominee Donald Trump on a sanitation truck outside Trump Tower in New York City Getty President Trump protests A woman yells as she takes part in a protest against President-elect Donald Trump in Seattle's Capitol Hill neighborhood AP President Trump protests A man dressed in red-white-and-blue sits on the curb during a protest against President-elect Donald Trump in Seattle's Capitol Hill neighborhood AP President Trump protests A protester sets off fireworks during a protest against President-elect Donald Trumpin Seattle's Capitol Hill neighborhood AP President Trump protests University of California, Davis students protest on campus in Davis, California, U.S. following the election of Donald Trump as President of the United States Reuters President Trump protests An Oakland police officer checks out damage after a window was broken by protesters at a car dealership in downtown Oakland, Calif AP President Trump protests A protester faces a police line in downtown Oakland, Calif AP President Trump protests President-elect Donald Trumpís victory set off multiple protests AP President Trump protests A fire burns during protests in Oakland, Calif AP

“Our country is having a bad time and it’s probably going to get worse,” one man said. "But we'll stick together and it will get better. So keep the faith."

Protesters briefly shut down motorways in Minneapolis and Los Angeles, rallying outside Philadelphia’s City Hall.

Roughly 500 people turned out at a protest in Louisville, Kentucky and in Baltimore, hundreds of people marched to the stadium where the Ravens were playing a football game.

Hundreds of protesters also demonstrated outside Trump Tower in Chicago and in Oakland, California, Dallas, Texas and elsewhere.

More demonstrations were expected on Friday night in both Democrat and Republican-voting states, as Mr Trump’s team starts the transition to his new administration ahead of inauguration in January.