Some 200 protesters gathered outside Donald Trump's New York City headquarters on Sunday, accusing the presidential hopeful of "fascism" and "racism" following his call for Muslims to be barred from entering the United States.

"Say no to fascism. Say no to Trump," read placards held by some of the demonstrators outside Trump Tower — the Fifth Avenue offices of the real estate magnate's business empire, which also doubles as his campaign headquarters.

A group of Muslim demonstrators kneeled in prayer outside the building as part of their protests.

"We started holding our protests in July, when Trump said Mexicans were drug dealers, criminals and rapists," one of the demonstrators, Jaime Gonzalez, 34, said.

"Today we're here because his offensive remarks about the Muslim community."

Counter-demonstrations were also held by a small group of Trump supporters outside the building.

The billionaire former reality TV star, 69, leads most Republican presidential polls by a sizeable margin.

Mr Trump's popularity has only grown in recent months, despite a succession of controversial statements that political pundits had believed would damage his standing with voters.

AFP