"It was a moment of frustration," Zambrano said Monday in an interview with ESPN. "I was trying to fire up the team. Lee told me to shut up, and I got more excited. I apologize from the bottom of my heart. The last person I would be mad at is D. Lee; he's a Gold Glover. I was just mad at myself."
Zambrano said he has already apologized to Lee.
"I texted Lee two days after it happened, and we talked after that," Zambrano said. "I apologized to him, and he responded well. He's a professional. He's one of the best teammates you can have."
Zambrano will apologize to the rest of his teammates when he rejoins the Cubs on Friday in Denver against the Colorado Rockies. He hopes he and the Cubs can move on after the apology.
"If I play better and do the right things, everything will be fine in Chicago," Zambrano said. "I love the fans and the city. I do not want to leave Chicago. I came on a mission, and I want that ring."
Undergoing anger management therapy is part of his road back to the major leagues, and Zambrano said the sessions have made a difference.
"A lot of people have told me I need to change if I want to be successful," Zambrano said. "Thank God the Cubs have sent me to the doctor for anger management. I've had three sessions already ... doing exercises. I have to write down every time I get mad."
Zambrano, who signed a five-year, $91 million contract extension in 2007, was pulled from the starting rotation earlier in the season and spent five weeks pitching out of the bullpen. His return to the starting rotation didn't fare much better as he went 2-3 with a 5.01 ERA in five starts before the suspension. He is 3-6 with a 5.66 ERA this season.
Zambrano has made two appearances for the Triple-A Iowa Cubs as he works his way back to the major leagues, and his promotion couldn't come soon enough.
"I'm really looking forward to being back with the team," Zambrano said. "I'm not liking Triple-A too much."