Having been cited, he appeared at an International Rugby Board disciplinary hearing on Sunday afternoon, where IRB judicial officer Michael Cashman, in a written judgement, determined that the first strike was to a player's head.
"The player admitted breaching Law 10.4 (a) for twice striking his opponent with his knee. He denied striking the other player's head," read a statement.
"The judicial officer determined the first strike was to the other player's head. After considering submissions from Jamie Heaslip and his legal representative, Michael Cashman assessed the offending to be in the mid-range of seriousness and, after taking relevant mitigating factors into account, he imposed a suspension of five weeks."
The ban, which runs up to and including July 17, rules Heaslip out of Ireland's upcoming games against New Zealand Maori (Friday, June 18) and Australia (Saturday, June 26).
Ireland team manager Paul McNaughton said: "To have him red carded so early in the game was crucial, although not an excuse. We're disappointed about that.
"But we went to the hearing and Jamie put his hand up in terms of the offence and we were happy with the way the judicial inquiry went."
McNaughton explained that Heaslip had apologised to his team-mates after the game and that the incident was 'completely out of character' for the Naas man.
"He's very disappointed that his tour is over and about the game, and that he can't participate in the next two games, especially the game against Australia.
"He feels he's let the guys down as well in relation to yesterday's game. In fact, he apologised to the rest of the squad and the team immediately afterwards.
"He's never been cited or red carded in his professional or amateur career, so it is completely out of character.
"The judicial officer came in with a medium level ruling and they also took into account his being contrite and owning up to it and his attitude at the tribunal itself."