A Sanzar judiciary committee has found Collins' punching excessive and disproportionate to the threat from the opponent.
The committee banned Collins from all rugby until September 10, ruling him out of Saturday's Test at Eden Park.
The committee noted Collins was one of the principal antagonists during the melee and continued to punch Van der Westhuyzen even after the South African had fallen to the ground.
Graham Henry must look to defeat Australia in Auckland and claim the Tri-Nations title without one of the most influential players of his campaign.
Waikato loose forward Sione Lauaki is expected to replace Collins, having acted a non-playing replacement at Carisbrook.