JACKSONVILLE, Fla. – Barack Obama has a message for America’s youth: Pull up your pants!

In an interview with MTV’s Sway Calloway, Obama fielded a question from Eric, a Huntington Beach, Calif., man who referenced a town ordinance that tried to outlaw a street fashion trend in which young men wear their baggy pants down well below their underwear.

Obama said such laws were “a waste of time,” but didn’t hold back on his own view on the fad.

“Having said that, brothers should pull up their pants,” he declared. “You are walking by your mother, your grandmother, your underwear is showing. What’s wrong with that? Come on.”

“Some people might not want to see your underwear – I’m one of them,” he added.

“Here is my attitude. I think people passing a law against people wearing sagging pants is a waste of time. We should be focused on creating jobs, improving our schools, health care, dealing with the war in Iraq.”

“Any public official that is worrying about sagging pants probably needs to spend some time focusing on real problems out there,” he said.

Although Obama doesn’t usually cast himself as the parenting police, he has gotten some of his biggest applause at rallies by telling parents to make their children turn off the TV.

Stressing responsibility is a page from the playbook of Bill Clinton, who came out for school uniforms. (Clinton also had a famous MTV underwear moment in the 1992 campaign, when he was asked whether he wore boxers or briefs.)

A Florida judge threw out a saggy-pants law in Riviera Beach, Fla., in September after a teen was arrested for showing four to five inches of his boxers.

After Obama’s underwear comments, Calloway asked about people who get fired for tattoos or dreadlocks.

Calloway wears long dreadlocks, which Obama said “looked tight.”

“It’s one thing if an employer discriminates on the basis of gender or sexual orientation or obviously, race or ethnicity,” Obama said, adding it was OK for employers to set standards.

He noted that his daughter Malia wears twists in her hair.

“To me, it looks great. Obviously, I would be upset if she were discriminated against on that basis,” Obama said.

geoff.earle@nypost.com