American protesters have rallied in Philadelphia, Pennsylvania, as US President Donald Trump travels to the city to attend a GOP policy retreat.

Thousands of demonstrators gathered in Center City, a district in Philadelphia, as the three-day the Congress of Tomorrow Republican Member Retreat got underway on Thursday.

"If we don't get no justice, they don't get no peace!" protesters chanted as they rallied in downtown Philadelphia.

On Thursday afternoon as Trump arrived to speak at the convention, the demonstrators marched toward the Loews Hotel, which is hosting the retreat, to hold a rally outside the hotel.

Protesters march near the Loews Hotel in Philadelphia where US President Donald Trump was speaking on January 26, 2017. (Photo from social media)

Chanting "Hey, hey, ho, ho, Donald Trump has got to go" and "Love not hate, that's what makes America great," the protesters walked from just north of City Hall to the nearby Loews Hotel, where Republican House and Senate lawmakers are holding their annual policy retreat.

The protesters carried placards condemning Trump for his controversial remarks about women and immigrants. The crowds were diverse in age and race and also included a group of disabled people.

Trump’s election campaign had been hit with many controversies since its inception in early 2015. But he still managed to stun the world by defeating the heavily-favored Democratic candidate, Hillary Clinton.

Protesters march in Philadelphia where the Congress of Tomorrow Republican Member Retreat got underway on January 26, 2017. (Photo from social media)

Thousands of people since then have rallied in cities across the US to protest against Trump's victory, condemning his campaign rhetoric against Muslims, immigrants, women and other groups.

The real estate mogul's controversial comments include a call to ban all Muslims from coming to America as well as stopping Mexican migrants by building a long wall along the US-Mexico border.

US President Donald Trump gives a thumbs-up as he arrives on Air Force One in Philadelphia, Pennsylvania, on January 26, 2017. (Photo by AP)

Trump has also angered many millions of Americans by vowing to repeal Obamacare.

Human Rights Watch has called on Trump to repudiate controversial proposals he made during the election campaign, saying that, if implemented, they would harm millions of people in the US and beyond.