James, playing in his 1,082nd career game, was tossed with 1:59 remaining in the third quarter and the Cavs leading 93-70.
After getting a steal, James dribbled upcourt and missed a layup then argued with referee Kane Fitzgerald that Heat forward James Johnson fouled him on the attempt. Fitzgerald assessed James with a technical foul and ejected him from the game.
"I got fouled all the way up the court, from the time that I stripped him, all the way until I got to the rim," James said of the sequence leading up to his ejection. "I said what I had to say and then I moved on, but he decided I should get [ejected]. It is what it is. We got the win, and that's what's most important."
Fitzgerald explained the rationale behind his decision to a pool reporter after the game.
"It was a culmination of a couple different acts," Fitzgerald said. "Immediately after the no-call, he turned and threw an air punch directly at me, and then he aggressively charged at me, and then he used vulgarity in my ear a few times."
Asked if anything happened between him and James before the third quarter that fed into the ejection, Fitzgerald said, "Nothing at all, nothing that I'm aware of."
At the time of the ejection, James had 21 points on 10-for-16 shooting, 12 rebounds and 6 assists but had attempted only one free throw.
"I think I'm one of the league leaders in points in the paint. I drive just as much as anybody. At this point, it's almost like they're trying to turn me into a jump shooter," James said of how he has been officiated this season. "I can't be a jump shooter. I'm not a jump shooter."
James' 5.4 free throw attempts per game are a career low, and his 19.0 field goal attempts per game are his most since 2009-10.
As for paint attempts, James entered Tuesday with 176 shots within 3 feet of the basket, behind only Milwaukee Bucks star forward Giannis Antetokounmpo, who averages three free throw attempts more per game than James.
Last season, several Cavs teammates spoke out on James' behalf when he wasn't receiving the calls they felt he deserved.
Asked about arguing with an official when the Cavs were up by 23, James said, "I'm trying to win every possession. I don't care if we're up 23 or we're down 23. I want to win every possession."
Cavaliers coach Tyronn Lue did not protest Fitzgerald's decision to eject James.
"Yup," Lue said. "Should have got thrown out. Yup. ... I really don't know what he said. He got kicked out. Want me to go against the ref? No, he got thrown out. He's out."
Lue later joked that James getting thrown out was one way to easily manage his star's minutes.
Dwyane Wade said he was surprised to see James on such a short leash with the official.
"I mean, I just thought it was quick," Wade said. "I mean, a player like him, you give him the benefit of the doubt. He says something, you give him a tech, kind of walk away and let him calm down. That's it. That's all I got on that."
Wade was asked if he had ever seen James that mad before in their five seasons as teammates.
"You know what, yes. I just ain't never seen him get ejected," Wade said. "But I've definitely seen him that mad before."
New York Knicks center Enes Kanter, who clashed with James earlier this month after James referred to himself as "the King of New York," might raise James' ire even more with the way he reacted to the ejection on Twitter.