Justin Bieber has laughed off his challenging of Tom Cruise to a UFC-style cage fight, saying he was "just playing".

The singer had previously tweeted that the actor would "never live it down" if he turned down the match.

But in a video posted by celebrity website TMZ on Wednesday, Bieber told paparazzi that he had seen an interview with Cruise and the star was "just on my mind".

"It was just a random tweet," he explained. "I do that stuff sometimes."

"I think he'd probably whup my ass in a fight!" he continued, laughing. "I'd have to get in some good shape." 

"I think he'd probably be out of my weight class," Bieber added.

"He's big, you know, he's got that dad strength."

Bieber had written on Monday: "I wanna challenge Tom Cruise to fight in the octagon. Tom if you don't take this fight your [sic] scared and you will never live it down. Who is willing to put on the fight?"

He also tweeted UFC president Dana White, asking for help setting up the fight.

Former two-weight champion Conor McGregor offered to host the match, posting: "If Tom Cruise is man enough to accept this challenge, McGregor Sports and Entertainment will host the bout."

The Irish sportsman questioned Cruise's fighting skills, adding: "Does Cruise have the sprouts to fight, like he does in the movies?"

Cruise famously performs his own stunts and broke his ankle while filming scenes for the Mission: Impossible film Fallout.

Bieber released a new single with Ed Sheeran last month, while Cruise will next be seen in Top Gun: Maverick, a direct sequel to the 1986 movie.

Click here for more music news.