Rodman, 51, in North Dakota for a promotional event, told KXJB-TV, Fargo, in an interview Monday, "I don't condone what he does, but he's my friend."
A spokesman for Rodman said the invitation to return was offered during his visit to North Korea two weeks ago.
The visit came at a time of heightened tension between the United States and North Korea, over North Korea's pursuit of a nuclear program, CNN said Tuesday.
Rodman and Kim sat together at a basketball exhibition in Pyongyang on Feb. 28, days before North Korea announced it would scrap the Korea Was armistice agreement and threatened South Korea with war.
Kim is known to be a basketball fan, CNN said.
The flamboyant Rodman helped the Detroit Pistons and Chicago Bulls win five NBA titles, and after his retirement from the NBA was elected to the Basketball Hall of Fame.