Chief executive Bruce Robertson said the law changes were diverse and complex.
"The timing is a little problematic. Introducing major changes to liquor legislation 10 days out from Christmas and New Year is not that good for anybody - it's a tough ask."
The bill set national trading hours of 7am to 11pm for bottle shops and 8am to 4am for bars and restaurants.
About 1000 premises hold 24-hour licences in New Zealand.
Mr Robertson was concerned about new licence fees which reflected the "risk" of a venue.
At present, all sellers of alcohol pay the same licensing fee, but the bill would introduce new charges based on a venue's size, trading hours and previous conduct.
"These will have costs associated with them at a time when the industry is struggling pretty hard.
"There's no fat there ... and some businesses might be forced to close," Mr Robertson said.
Bars, restaurants and liquor stores would not know of the specific changes for 12 months because the bill also gave new powers to communities to set their own rules.
Territorial authorities would be able to introduce different trading hours to the national limits, ban entry to clubs after 3am, or prevent liquor stores from opening near schools.
Auckland Mayor Len Brown welcomed the final stages of the bill.
He had urged the minister to pass the legislation as soon as possible to help curb antisocial behaviour caused by drinking in parts of Auckland.
Mr Brown organised a taskforce in June to combat alcohol harm, and said some of the taskforce's initiatives, such as one-way door policies in clubs, could now be considered by communities throughout the city.
The Labour Party sought national-level alcohol policies that helped protect communities.
Its South Auckland MPs tabled amendments to ban alcohol sales near schools, but these were voted down.
Mrs Collins said at the time it was not a good idea to set universal rules because poor suburbs such as Manurewa would want tougher limits than wealthy areas like Remuera.
The New Zealand Drug Foundation welcomed the introduction of local alcohol policies, but wanted them to be made compulsory.
The foundation believed the cost and lengthy process of drafting a policy would prevent communities from making changes in their area.
Alcohol reforms
What are the main changes?
New powers for communities to set their own rules on alcohol, bans on grocery stores selling liquor, ban on sale of alcohol from bottle shops between 11pm and 7am and in bars from 4am to 8am, restricted advertising of alcohol in supermarkets, express consent from parents needed for minors to drink, and licence fees charged according to the "risk" associated with a venue.
How will the changes affect bars and their managers?
Bars will not be able to stay open between 4am and 8am unless their local community decides to allow longer trading hours. One-way door policies or even stricter hours could also be introduced if communities wish. Bars or managers who break liquor laws three times in three years could have their licence or certificate cancelled for five years. Licence fees will be decided according to a venue's past record.
How will the changes affect buyers?
Alcohol will not be available to buy between 4am and 8am and beer, wine and spirits will no longer be available from grocery stores.
How will the changes affect parents and minors?
Parents must give express consent to underage children to consume alcohol. If they fail to supply alcohol in a responsible manner they are liable for a $2000 fine. People using fake ID or lending ID for alcohol consumption face fines or prosecution.
How will the changes affect the alcohol industry?
The industry must draw up a code for sale of ready-to-drink beverages. It it does not, Government may step in and set limits on the sale of "alcopops".
When will the changes occur?
Some in six months, but most will be implemented in 12 months.
