Hundreds of protesters have jostled with police in riot gear outside a California hotel ahead of a speech by Republican presidential frontrunner Donald Trump, forcing the candidate to duck into a back entrance.

Key points: At least five protesters arrested at anti-Trump rally

At least five protesters arrested at anti-Trump rally "We are not all like the way he thinks we are," one demonstrator says

"We are not all like the way he thinks we are," one demonstrator says Mr Trump forced to hop over a barrier and use back entrance to the hotel

Protesters broke through barricades set up around the hotel near San Francisco's international airport where the California Republican Convention was taking place.

Police guarding the entrances were able to stop them from entering the hotel.

The demonstrators waved banners that read "No hate, no racism, no Trump", "We need a uniter, not a divider" and "Trump is the modern day Hitler". Several carried Mexican flags.

Some protesters lobbed eggs at officers, and at least five were arrested, a police spokesman said.

Several demonstrators and police officers suffered minor injuries, he added.

The tense protest in Burlingame follows similar demonstrations that turned violent on Thursday at another Trump campaign rally in southern California.

Ahead of the San Francisco convention, police blocked the roads near the hotel hosting Mr Trump's speech and formed a security cordon to keep protesters from entering.

Police hold back anti-Trump demonstrators outside the Hyatt hotel in California where he spoke. ( By Noah Berger )

"I am here because I don't like all the bad stuff Trump has been saying lately about immigrants and Latinos," said Eric Lopez, one of the demonstrators.

"We are not all like the way he thinks we are."

Jorge-Mario Cabrera, spokesman for the Coalition for Humane Immigrant Rights of Los Angeles, denounced Mr Trump's rhetoric and said he hoped the real estate magnate would be defeated at the polls.

"The community is sick of being denigrated, disrespected and attacked," he said in a statement. "Nevertheless, our reaction should be to march peacefully, as we have always done, and vote at the polls."

'Not the easiest entrance I've made'

Mr Trump was forced to abandon his motorcade on a nearby highway, hop over a barrier and use a back entrance to the hotel, surrounded by security guards.

Sorry, this video has expired Donald Trump speaks after using a back entrance into the hotel

"That was not the easiest entrance I've ever made," he said during his speech at the convention.

"My wife called, she said 'there are helicopters following you'... and then we went under a fence and through a fence and, oh boy, it felt like I was crossing the border actually."

After delivering his speech without incident, Mr Trump was again escorted out the back entrance.

The protest followed similar demonstrations on Thursday, where about 20 people were arrested outside the Orange County amphitheatre in Costa Mesa during a Trump campaign stopover, which drew a crowd of thousands ahead of the state's June 7 primary.

The demonstrators hurled rocks at passing vehicles and vandalized cars, smashing at least one patrol car's window and puncturing the tires on another.

California, which votes on the last day of Republican primaries, is crucial in Mr Trump's push to secure the number of delegates he needs to win the Republican presidential nomination outright.

Protesters have disrupted campaign rallies for Mr Trump across the country, denouncing the frontrunner's rhetoric against Muslims and immigrants.

The billionaire developer has outraged many by comparing Mexican immigrants to "rapists" and has vowed to build a wall along the Mexican-American border to prevent illegal immigration.

Two men sell eggs during the anti-Trump protest outside the Hyatt Regency Hotel. ( AFP: Josh Edelson )

AFP