Ibaka, the Oklahoma City Thunder's power forward, said Monday that James was "not a good defender" and that "he can play defense for two or three minutes but not 48 minutes." James responded to the comments before Tuesday's Game 4 of the NBA Finals.
"I don't really care what he says, he's stupid," James said. "Everyone says something to me every series, then (the media) tries to get a quote. It's stupid."
Ibaka made the comments to The Palm Beach Post.
"LeBron can't play (Kevin Durant) one-on-one. They're playing good defense like a team," Ibaka told the newspaper.
In addition to the Finals, James and Ibaka likely will face off this summer at the Olympics. Ibaka plays for the Spanish national team, expected to be the most serious challenger to Team USA's bid to repeat as gold medalists.
The Heat have been rotating defenders on Durant, who is averaging 31 points on 57 percent shooting in the series, but James was his primary defender in the fourth quarter of the Heat's 91-85 Game 3 victory on Sunday. Durant was 1-of-5 shooting in the quarter with James guarding him.
"For me as a defender, I just try to make plays and try to keep my body in front of a great player," James said. "First of all, I'm not playing 48 minutes, and Kevin's not playing 48 minutes. I'm not guarding him for 48 minutes. When I'm on him, I'm just trying to make it tough for him to make shots, which he's going to make."
In other Thunder-Heat player beef news, Heat forward Chris Bosh said there's no longer any bad blood between him and Durant. Last year Durant referred to Bosh when he said, "There are a lot of fake tough guys in this league, and he's one of them," after the two got in an exchange on the court at a game in Oklahoma City.
"We squashed that at the last All-Star Game," Bosh said Tuesday.