A teenage waitress who was racially abused by a customer for being Māori is calling on him to "own his racism" and come forward and apologise.

On Monday last week Mia Griffiths, 17, was serving a table at a popular Viaduct restaurant that included the leadership team from building materials company James Hardie and their partners.

As part of her part-time job Mia, who is in Year 13, needed to explain the menu, which included dishes such as Kaipara lamb.

One man picked up on her correct Māori pronunciation, before launching into a racist tirade.

"He said things like, 'Where are your whānau? I bet they don't eat here often, they are at home eating boil-up'.

"I said, 'Actually they eat here quite a lot', but they just laughed even more."

Mia, who is saving to study medicine next year, said it left her "absolutely shocked".

"I was kind of speechless, I didn't know what to do or say."

The worst thing was nobody at the table stood up to the man, believed to be the partner of a senior staff member, with many of them laughing and even joining in the comments, she said.

"They were almost egging him on. Even if I said something, they were just laughing so hard."

Mia raised the issue with a duty manager and finished her shift early because she was so upset.

One of the restaurant owners told the Herald a James Hardie representative had sent them a written apology. They had also worked with the company to identify the man who made the comments and his partner, and they had been banned from the restaurant.

"We feel the apology was genuine. We also wanted to issue the ban to make sure our restaurant is a safe space.

"This was a first for us, and now we are working with our team to ensure they are okay, and make sure we have the right processes in place.

"We are a really multicultural workplace and fully support Mia, that she has a voice on this, and want to do all we can to stand up to everyday racism."

However, there had been no direct apology from the man to Mia.

"He needs to own up to his racism and apologise," Mia said.

"I might just be one person, but who knows how many others he has done this to? He needs to know the effects his comments have on people."

The comments had played on her self-esteem and affected her at school this week, Mia said.

"I keep thinking, 'I should have said something'. But when it is at work, you are just not sure what to do in the moment."

James Hardie has not responded to multiple requests from the Herald for comment.

Mia's mother, Kiri Turketo, principal at Sir Edmund Hillary Collegiate, said it was "despicable" behaviour by the man, and also the table that did not defend her daughter.

"That was a table full of their senior leadership team, and nobody said anything.

"Even the man's partner did not stick up for her, as he abused a young woman in front of her.

"They laughed at her and her cultural heritage, made jokes about her being Māori and for pronouncing Māori words correctly, as we have taught her."

Turketo said the restaurant had been "amazing" in its support following the incident, meanwhile the response from James Hardie had been "disappointing".

Turketo had contacted the company directly and asked for an apology from the man and his partner, a staff member, but to no avail.

"It was a violent, verbal assault on someone's cultural identity. He needs to come forward and apologise.

"We weren't going to say anything but then thought, we should not have to put up with this.

"As Taika Waititi said, 'New Zealand is racist AF'."

Turketo said she would be laying a complaint with the Human Rights Commission.

A Human Rights Commission spokesman said the complaints process was confidential and they did not comment on individual cases.

"In general terms, we are always concerned to hear about situations when people, particularly young people, feel that they have been racially harassed.

"Racism has no place in New Zealand but, disturbingly, one in three complaints to the Human Rights Commission are about racial discrimination."