Certain flavours will be phased out, except at specialist retailers over the next 15 months.
Cancer Society advocacy and wellbeing manager Shayne Nahu said the changes would make a big difference.
"We are seeing promotions at events that were really targeting young people, a number of the promotions are coming across as [if] they are cool vibrant products, almost like a lifestyle choice, which is not what they're about, they're there to help smokers stop."
They should not be perceived as a recreational choice, Nahu said.
The regulations would be a relief to school principals, teachers and parents who had been looking for regulation, he said.
"We've had two years without regulation and that has allowed the tobacco industry to get a foothold on the messaging around vaping.
"Vaping is not harmless, these laws will play a vital part in protecting children and non-smokers from a highly addictive product they simply don't need, while supporting people who smoke to switch and quit."
The law change was a good step, but more needed to be done about tobacco products, Nahu said.
"We are waiting on a smoke-free action plan from the Government, that is going to be great and we are expecting to see some bold initiatives in there so we can get to smoke-free 2025 for a healthier New Zealand/Aotearoa."
The Cancer Society looked forward to the day when all tobacco products were only available from specialist R18 shops, he said.
