Allen received a technical foul on the play. He was in near hysterics on the bench afterwards, but remained with the team and then played in the second half of Duke's 72-61 win over Elon.
"We have had the opportunity to thoroughly review the incident involving Grayson Allen from last night's game against Elon," Krzyzewski said in a statement.
"As I stated last night, the incident was unacceptable and inexcusable. He took an important step last night by apologising in person to Steven Santa Ana and coach Matt Matheny.
"As a programme, we needed to take further steps regarding his actions that do not meet the standards of Duke Basketball. To that end, we have determined that Grayson will be suspended from competition for an indefinite amount of time."
This was a slight change in tone from Krzyzewski and his immediate response after the game, when he pointed out that Allen had apologised and spoke about viewing this as a teaching moment.
"I had a long talk with him afterwards," Krzyzewski said. "And the right thing to do was to apologise in person."
Allen was emotional, as he apologised for the latest incident after the game.
"I mean, I don't plan on doing it again," Allen told AP, as he fought back tears. "I made another mistake. I have to try to be better again, just like I tried to be better from last year."
"I made a really bad play," Allen said. "I'm sorry to him, Santa Ana. I'm sorry to the officials who have to call that.
"I'm sorry to my team, it's selfish and it took away from them. I'm not proud of it at all."
Some of Grayson Allen's other career lowlights:
