According to police and witnesses, Moby, whose real name is Richard M. Melville, was approached by the men about 1 a.m. Thursday outside the Paradise Rock Club. One of the men punched Moby in the back of the head and on the right side of his face, breaking the singer’s glasses and cutting and bruising his face.

When two club security guards tried to stop the attack, the assailants sprayed a mace-like substance at Moby, Moby’s manager and the guards, and then fled, police said.

Moby, 37, declined medical attention.

The assailants said nothing during the attack, and the motive is unknown, said Paradise manager Jeff Marshall.

In recent months, Moby has feuded with rapper star Eminem.

At last year’s Grammys, Moby called Eminem a “racist,” “misogynist” and a “homophobe.” At this year’s MTV Video Music Awards, Eminem said of Moby from the stage, “I will hit a man with glasses.”

A publicist at Eminem’s record company said Thursday it would be “ridiculous” to think the attack would have been prompted by the singer’s statements.

“That is one of the more ridiculous things I’ve ever heard,” Dennis Dennehy, head of publicity at Interscope Records, told The Boston Globe on Thursday. Dennehy and other Interscope publicity officials did not immediately return telephone calls to The Associated Press on Friday.

Boston police said they have no reason to believe the attack was instigated by a tiff between the musicians.

“This doesn’t seem to have anything to do with anything like that,” said officer Nadine Taylor-Miller.

During the concert, Moby, a self-described pacifist, had spoken out against aggression and violence.

He wrote on his Web site that he is not angry about the attack, just mystified about the motive. He has asked the attackers to post an explanation.

“And if anyone sees me in the next couple of weeks and I have some big bruises or stitches on my face, well at least you know why,” Moby wrote.

Moby is electronic music’s first bona fide superstar. His 1999 album Play sold 10 million copies. For the past two years, the Connecticut native has headlined a touring festival that has featured guests such as David Bowie.