The NBA announced the suspension Saturday, two days after Oubre was ejected from Washington's Game 3 blowout victory for shoving Boston's Kelly Olynyk.
After being floored by an illegal screen from Olynyk early in the second quarter Thursday, Oubre charged at Olynyk and knocked him to the ground by burying his forearm in his chest. Oubre was assessed a flagrant 2 and ejected.
Oubre called the suspension a consequence of his actions.
"I'm not surprised," he said after practice Saturday. "The league has to do what they have to do. They have to handle that situation."
The 21-year-old said he apologized to referee Monty McCutchen, who was talking to Olynyk at the time of the incident. Oubre said he did not reach out to apologize to Olynyk.
Oubre said Friday that he retaliated against Olynyk because he had been hit repeatedly by the Celtics center.
"I've been hit in the head multiple times by the same person," Oubre told reporters. "I've confronted [Olynyk] about it. The last time it happened, I fell, I felt pain in my head and my jaw, and I got up and I ran to him and I bumped him."
Olynyk disputed Oubre's claim that they talked before the incident and said he sensed that Oubre was becoming frustrated on the court.
"You could see it when he was guarding, trying to run through screens," Olynyk said. "I think he kind of flipped a switch."
Olynyk was asked if he knew Oubre much before the flare-up.
"I don't really know him that well. I thought he was a good guy," Olynyk saod. "Like I said, all that stuff is in the past now. It doesn't really make a difference. Hopefully we can go in and get Game 4."
The Wizards routed the Celtics 116-89 in Game 3, but they still trail 2-1 in the best-of-seven Eastern Conference semifinal series. Game 4 is Sunday in Washington.
Washington coach Scott Brooks said he respects the league's decision and figured a suspension could be coming. Now he must decide how to approach Game 4.
"We've had a next-man-up mentality all year," Brooks said Saturday. "We've got options, we can move some people around. But not having [Oubre], it's not ideal, but it is what it is. You just go forward and play the game. You can't worry about who's not playing."
Oubre, a 6-foot-7 forward, is averaging 6.3 points and 17.4 minutes per game in the playoffs. Brooks could find more minutes for Bojan Bogdanovic after the sharpshooting forward scored 19 points in Game 3. Or he could plug another player, like Jason Smith, into the rotation.
"I'm looking at all options -- maybe give some extra minutes, maybe add another guy, maybe change some spots on the floor with different players playing different positions," Brooks said. "Those are all on the table right now."
The Celtics and Wizards racked up a combined 16 technical fouls during their four regular-season matchups. Thursday's game featured eight technical fouls and three ejections.
Celtics coach Brad Stevens said he didn't have any reaction to the news. Pressed on how Oubre's absence might affect the game, Stevens said the Celtics have to "play better than we did the other day, regardless of who's playing."
Stevens did praise both teams for the way they responded after Oubre's outburst, noting things could have gotten a lot messier if cooler heads didn't prevail.
"I thought [Olynyk] did an unbelievable job keeping his emotions cool in that moment," Stevens said. "I credit all the guys that were on the court, both teams, after that. I thought that could have started something a lot worse than it started, because nobody saw that coming. So I thought both teams kept their cool in that moment for sure."
ESPN's Chris Forsberg and The Associated Press contributed to this report.