Psy is apologising to Americans for participating in anti-US protests several years ago.
Park Jae-sang, who performs as Psy, issued a statement on Friday after reports surfaced that he had participated in concerts protesting the US military presence in South Korea during the early stages of the Iraq war.
Psy says sorry
At a 2004 concert he rapped about killing "Yankees" who have been torturing Iraqi captives and their families.
The 34-year-old Gangnam Style rapper said the protests were part of a "deeply emotional" reaction to the war and the killing of two Korean schoolgirls.
He said he "will forever be sorry for any pain I have caused by those words."
Earlier, the White House confirmed President Barack Obama and his family will attend a charity concert on December 21 where PSY is scheduled to perform.