"I sincerely regret my actions and the unfortunate use of words during the recent incident on (the) set," the 43-year-old actor said in a statement to People magazine. "Both are beneath my own personal standards. ... I have nothing but respect for my co-workers ... and have apologized personally to everyone involved."
The magazine, citing a source on the set, reported Wednesday on its Web site that when T.R. Knight was late to film a scene, a debate ensued between Dempsey and Washington, with Dempsey insisting on waiting for Knight. The argument quickly intensified, and an alleged homophobic slur was used, but Knight wasn't present.
Washington plays Dr. Preston Burke and Dempsey, 40, plays Dr. Derek Shepherd on the ABC drama. Knight, 33, plays an intern, Dr. George O'Malley.
"Differences are inevitable," Washington's publicist, Cynthia Snyder, said in a recent statement. "They were aired, resolved and everyone has moved on."
The clash occurred Oct. 9. Knight revealed Oct. 19 that he is gay.
"I guess there have been a few questions about my sexuality, and I'd like to quiet any unnecessary rumors that may be out there," Knight said in a statement. "I hope the fact that I'm gay isn't the most interesting part of me."
Shonda Rhimes, creator of the show, is downplaying the incident. It "was 4½ seconds of one day in three years," she told People. "I feel like we've already moved on."