The plan would see only the over 21s being able to buy alcohol from a shop
Plans to raise the age at which young people can buy alcohol from shops from 18 to 21 have come under further pressure at parliament.
A coalition of student and young person's groups said the Scottish Government plan would demonise young people.
They made the call before Holyrood's petitions committee.
Ministers said raising the age worked well in Scandinavia and three areas of Scotland where it was trialled.
The government's under-21s sales ban is part of a number of measures to cut alcohol-fuelled crime and health problems, including setting a minimum price for alcoholic drinks in an attempt to stop cut-price alcohol deals.
The move has been backed by members of Scotland's medical profession.
MSPs on the petitions committee considered a 10,000-signature petition from the Coalition Against Raising the Drinking Age in Scotland (Cardas).
The group said the proposal was sending out a "bizarre message" that young people were responsible enough to vote, to get married, to join the Army and yet could not be trusted to buy a bottle of wine from a supermarket for a quiet dinner at home.
Labour, the Liberal Democrats and the Conservatives have all come out against raising the off-licence purchase age and the student representative on the SNP's national executive, Caroline Henderson, is against it.
Meanwhile, the number of people admitted to hospital in Lothian with alcohol poisoning has increased by half over the last 10 years - from 682 in 1998 to 934 last year, according to new figures.
Public health minister Shona Robison said those aged under 24 accounted for almost a quarter of the admissions.
"These figures are another reminder of the grip alcohol misuse has on Scotland," she said.
"Alcohol misuse costs the NHS £2.25bn each year. It's affecting our health system, our justice system and our economy."