Allen, who averages 18.2 points and 3.5 rebounds, served his suspension when the Celtics visited the Philadelphia 76ers on Tuesday. Allen will be docked more than $167,000 in salary. Kevin Garnett also missed the game to rest his strained knee.
Tempers boiled in the third quarter of Boston's 107-76 loss at Cleveland on Sunday when Varejao and Allen got tangled under the basket after a free throw.
Varejao flung Boston's guard to the floor, and Allen responded with a well-placed elbow into the forward's groin area. Both players jawed at each other before getting technical fouls.
"It was a dirty play," Allen said. "He locked my arm and threw me to the ground. I wasn't going to allow him to think he could do whatever he wanted. I'm always going to stand up for myself. It's one thing for a team to be beating us, but they're not going to walk all over us."
The frizzy-haired Varejao had his own take.
"You don't hit a man in his [groin]," he said. "He doesn't like Brazilians or he doesn't like my hair."
Celtics coach Doc Rivers said he was surprised Allen was suspended, but thought the target of the elbow played a role in the punishment.
"The bottom line to me is the foul before the incident," Rivers said. "If they'd call a foul, the incident may have never happened. I didn't know you could swing a guy around and sling him to the floor and that wasn't a foul."
Allen likely would have sat out the Sixers game anyway and Rivers said it was doubtful Allen or Paul Pierce would play in Wednesday's finale against Washington.
Information from The Associated Press was used in this report.