The previously unreported comment was disclosed by the TVNewser blog.
"Barack ... he's talking down to black people ... telling [black people] how to behave." Only Jackson used the plural form of the "n-word," not "black people," in the second part of his comment.
The longtime civil rights leader already came under fire this month for crude off-air comments he made against Obama in what he thought was a private conversation during a taping of a "Fox & Friends" news show.
Jackson, who is traveling in Spain, apologized in a statement Wednesday for "hurtful words" but did not offer specifics.
"I am deeply saddened and distressed by the pain and sorrow that I have caused as a result of my hurtful words. I apologize again to Senator Barack Obama, Michelle Obama, their children as well as to the American public," Jackson said in a written statement.
"There really is no justification for my comments and I hope that the Obama family and the American public will forgive me. I also pray that we, as a nation, can move on to address the real issues that affect the American people."