Mr McCarthy said his club paid particular attention to the statement in this year's handbook - "these rules will be strictly enforced during 2011." He emphasised they had taken Dagg out of the equation in making their decision.
"As a club we are well aware allowing Izzy to play this game would be good for All Black rugby and great for the promotion of the game.
However the reality is that the NZRFU's major responsibility is to the ABs with the HBRFU's main aim being the success of the Magpies.
"We would like to inform all concerned that as a club our main responsibility is to grass roots rugby - the players we manage at club level over a period of a season. We have, therefore, concluded this Saturday is all about the Havelock North club and the responsibilities we are obliged to carry out on behalf of all our players who take the field on behalf of the club," Mr McCarthy said.
"We struggle to accept Izzy cannot have game time for the Magpies tomorrow night in what we would consider a more structured standard of rugby where he is less likely to encounter injury problems."
Napier Pirate Rugby and Sports coach Phil Rumper said he would not play Dagg without approval from the Hawke's Bay and New Zealand unions.
"I don't want to risk losing the game under protest. If we do play Izzy it would probably be 20 or so minutes off the bench ... he's coming off a long injury spell."
Magpies co-coach Peter Russell said it was better for Dagg to play club rugby before returning to the Magpies and the All Blacks.
