The 22-year-old Guildford, a member of New Zealand's World Cup winning squad, was reported last month to have stormed into a Rarotonga bar bleeding and naked before punching two customers. He was not charged by local police.
The NZRU held a disciplinary hearing with Guildford and imposed the four-match sanction. Three of the games will be part of the Canterbury Crusaders' preparations for next year's Super Rugby season.
Guildford, who has previously come under fire for other drink-related incidents while in camp with the All Blacks, will miss only one competitive game, against the Auckland Blues on February 24.
"Taking players out of rugby is not something we do lightly. But we have taken into account the fact that with regard to alcohol-related behaviour, Zac does not have an exemplary record," NZRU professional rugby manager Neil Sorensen said.
"On this occasion, he embarrassed himself, his family, his team mates, and New Zealand Rugby. We believe Zac brought the game into disrepute and the sanctions reflect the gravity of the situation and the need for a real pathway to recovery.
"To his credit, Zac himself has agreed that he needs assistance and recognises that both the NZRU and the Crusaders support him taking time to get himself right."
Guildford would need to undergo alcohol counselling at his own expense, the NZRU added.
"I am embarrassed by what has happened, but I know that I let down the many people who support me," Guildford said.
"I am focused on getting myself into the place I need to be when I return to rugby next year."