"It's too late. I don't care to ever speak to him again," McGwire told ESPNLosAngeles.com on Wednesday. "What he did was wrong."
Canseco apologized to McGwire while attending the Oakland A's commemoration of the 25th anniversary of their 1989 World Series victory last weekend. He had accused McGwire of using performance-enhancing drugs in his 2005 book, "Juiced: Wild Times, Rampant 'Roids, Smash Hits & How Baseball Got Big." McGwire admitted to using PEDs in 2010.
It's not the first time Canseco has made a point of publicizing his efforts to reconcile with McGwire. In September 2012, he showed up at a St. Louis Cardinals game at Dodger Stadium wearing a black T-shirt that read, "Sorry for everything, Mark." At the time, McGwire was the Cardinals hitting coach.
"I can care less what he does," McGwire said.
McGwire, now the Los Angeles Dodgers hitting coach, said he got a text from former A's teammate Mike Gallego telling him he was missed at the ceremony. McGwire was with the Dodgers in St. Louis at the time. He and Dodgers pitching coach Rick Honeycutt, a key reliever on the '89 team, each taped video tributes to that A's team during spring training.
Canseco had not been at the Coliseum since his playing days ended.
"Mark, to me, when I played with him, I looked up to him," Canseco told reporters. "I idolized him for a lot of reasons -- the guy was on the field, he was off the field. It haunts me till this day that I said those things about him, even though obviously they were true. I could have gone about it a different way and gotten my point across."
Neither Canseco nor McGwire attended the team's 20-year anniversary, and Canseco said he has had no contact with McGwire since the book came out nearly a decade ago.
"I regret writing the book for sure," Canseco said. "I battled and fought with the thought of, 'I wish I never used chemicals or steroids.' But I don't see how back then when I was only 19, 20 years old, I didn't really know the situation."
Some of Canseco's former teammates were more forgiving, with Dennis Eckersley telling the Associated Press, "I mean, come on, man. It's been a long time. Time heals everything."
The A's swept the San Francisco Giants in the 1989 World Series, which was interrupted by a massive earthquake centered in the nearby Santa Cruz Mountains. The A's honored the team, their last championship club, on the field before Saturday's game against Baltimore.