Harrell, a junior who is averaging 14.9 points and 9.2 rebounds after deciding after last season to return to Louisville instead of opting for the NBA draft, had earlier told ESPN Radio 680 of the decision without giving any reasons.
"Absolutely no big deal," Pitino said in a message to The Courier-Journal. "Totally nothing. He is still the leader of our team."
The 6-foot-8 Harrell, who was one of 25 players named to the Wooden Award Midseason Watch List on Jan. 14, was suspended one game by the ACC earlier this season for throwing an elbow during a victory against Western Kentucky on Dec. 21.
Senior Wayne Blackshear is currently the Cardinals' lone remaining captain.