Doncic was tossed early in the third quarter after hitting Collin Sexton in the groin while boxing out on a shot from Isaac Okoro.
"After I saw the video, I knew I hit him, but it was nothing on purpose," he told reporters. "I think that kind of stuff happens a lot in the games, but I don't know. That's my explanation. It obviously was not on purpose."
The call was ruled a flagrant-2 foul and does not count toward the technical fouls that have been called on Doncic this season. One more technical foul and he will earn a one-game suspension.
Sexton seemed to agree with Doncic's assessment of the incident.
"It was just a box-out play," he told reporters. "Usually whenever someone is hand-checking, then you punch down or swing down. It was just in the groin, but it’s all good.”
Doncic had 15 points, five rebounds, five assists and some NBA history before he was tossed, becoming the third player in the league to post 5,000 points, 1,500 assists and 1,500 rebounds in his first three seasons in the league (h/t Callie Caplan of the Dallas Morning News).
The Mavericks went on to earn a 124-97 win.
The ejection was Doncic's second in five games. In a May 2 loss to the Sacramento Kings, he was whistled for two technical fouls.
After he earned his 15th of the season against the Brooklyn Nets on Friday, Doncic said he needed to keep his emotions in check when dealing with officials.
"It's something that I'm not supposed to do, with all the emotions in games, but obviously I've got to stop," he told reporters. "It's just hard for me on the court with all the emotions, but I realize it and I've got to work on this. It's tough to do it, but I've got to work on it and be way better than this."
With the Mavericks bound for the postseason at 40-28—good for the fifth seed in the Western Conference—losing their top player at any point down the line could have serious consequences.