The suspension of Whitelock, who had been captaining the Crusaders, will leave a leadership void in the team, with fellow All Black Kieran Read also sidelined due to injury.
Jamie-Jerry Taulagi of the Sunwolves also recieved a suspension, being banned for five weeks after a dangerous tackle on Chiefs back Shaun Stevenson.
"The Judicial Committee deemed the act of foul play merited a mid range entry point of four weeks due to the World Rugby stipulation that a strike to the head shall result in at least a mid range entry point sanction," the ruling read.
"However, taking into account mitigating factors including the fact that the player had an excellent disciplinary record including 110 Super Rugby games for the Crusaders and 84 test caps for the All Blacks, the Judicial Committee reduced the otherwise applicable sanction from four weeks to two weeks."