Heaslip, who admitted the offence but denied making contact with McCaw's head, is now banned until July 17 and will miss the matches with New Zealand Maori and Australia.
Ireland Under-20 captain Rhys Ruddock has been called up as a replacement while Shane Horgan and Jerry Flannery have also linked up with the squad.
Ireland team manager Paul McNaughton explained how Heaslip's behavior came as a shock to him and the team.
He said: "To have him red-carded so early in the game was crucial, although not an excuse.
"He feels he's let the guys down. He apologised to the rest of the squad and the team immediately after the game.
"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."