While introducing Obama to the assembled crowd at Chicago's Hyatt Hotel, Mac joked about having a black president and suggested members of the Republican Party play dirty, the Chicago Sun-Times reported Saturday.
"I don't know why my man Barack wants to be president but I'm proud of him because politics is dirty, especially with Republicans," he said.
Obama's electoral staff said the Democratic senator from Illinois called the "Guess Who" comedian on his choice of jokes.
"Senator Obama told Bernie Mac that he doesn't condone these statements and believes what was said was inappropriate," the campaign team said.
Obama thanked the comedian for the introduction, but later offered a mixed response to the questionable material.
"That means, by the way, Bernie, you got to clean up your act," Obama said after calling for increased equality. "This is a family affair. ... I'm just messing with you, man."