The All Blacks winger was banned for four games following an incident that saw him punch two men after arriving drunk, naked and bleeding at a bar in the Cook Islands capital of Nuku'alofa last month.
It marked the fourth time in 18 months that the 22-year-old Canterbury Crusaders winger had been involved in misbehavior related to alcohol.
As part of his punishment, he is required to undergo alcohol treatment and counseling at his own expense.
Guildford was suspended for the first four weeks of the season, although the ban encompasses three pre-season matches so he will be available to face the Highlanders on March 3.
"Taking players out of rugby is not something we do lightly," said New Zealand union's general manager of professional rugby Neil Sorensen. "But we have taken into account the fact that with regard to alcohol-related behavior, Zac does not have an exemplary record.
"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."
Guildford said: "I am embarrassed by what has happened, but I know that I let down the many people who support me. I am focused on getting myself into the place I need to be when I return to rugby next year."
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