Presidential race 'not reality TV': Obama

US President Barack Obama says his main role in the election is to remind voters "this is a serious job... not reality TV" in a jab at Donald Trump.

US President Barack Obama has told TV host Jimmy Fallon a presidential election is "not reality TV". (AAP)

A presidential election is "not reality TV", US President Barack Obama has said in an interview with late night talk show host Jimmy Fallon.

Obama praised Hillary Clinton, who had secured his Democratic Party's nomination, but did not endorse her outright ahead of a meeting on Thursday with rival candidate Bernie Sanders.

"The main role I'm gonna be playing in this process is to remind the American people that this is a serious job," Obama said, according to a transcript of the interview that is to air on Thursday.

"You know, this is not reality TV."

Obama said he had not spoken with presumptive Republican nominee Donald Trump.

Asked whether Republicans were happy with their divisive choice, Obama joked, "We are. But I don't know how they're feeling."

However, he said on a serious note that the situation among opposition Republicans "is not actually good for the country as a whole. It's not something Democrats should wish for."

He said he hoped the party could correct itself in future elections and return to its role as a centre-right party.

He also hoped divisions between Democrats start to heal during the next couple of weeks after a hard-fought campaign.

"My hope is that over the next couple of weeks we're able to pull things together," Obama said.

"What happens during primaries is you get a little ouchy," Obama told NBC late night host Jimmy Fallon during a taping of The Tonight Show set to air on Thursday.

Later, at a fundraiser in the Central Park West apartment of Kenneth Lerer, a venture capitalist and chairman of the BuzzFeed media company, Obama said he was "not too worried" about "bruised feelings" left over from the primary.

"We just ended - sort of ended - our primary season," Obama said, catching his mistake as the crowd of about 60 Democratic donors, who paid up to $US33,400 ($A44,700) to attend, laughed nervously.

"I am concerned about us doing the hard nuts-and-bolts work of turning out people to vote, particularly young people, particularly low-income people," Obama said.

Asked whether Obama thought Sanders, a US senator from Vermont, should quickly end his campaign, White House spokesman Josh Earnest said the senator had "more than earned the right to make his own decision about the course of his campaign".

The party will officially vote on Clinton's nomination at its convention in Philadelphia at the end of July.