The memo shared with SBS Arabic24 was circulated in November via a discussion group for senior staff members on the messaging platform WhatsApp.
In the correspondence addressed to “teams”, a senior NSW company representative said he had the “unfortunate task” of raising the issue after four reports were received in different restaurants.
The chain, which has 12 branches in NSW, is operated by South African-owned Seagrass Boutique Hospitality Group, which runs a number of high-profile restaurant franchises in Australia.
The memo continued by labelling the speaking of other languages by staff as "disgusting" and "disrespectful", and that it "speaks completely against our Seagrass Culture of #togetherness".
“BE WARNED: NATIVE LANGUAGE SPEAKING WILL NOT BE TOLERATED ANYMORE,” it said while calling on managers to “stamp this out” and “treat occurrences of this with immediate disciplinary action.”
The nature of the "disciplinary action" was not explained and the memo was signed off with the words, "ZERO TOLERANCE".

The message shared on WhatsApp. Source: Supplied
A media relations representative from Seagrass told SBS Arabic24 the message was being investigated.
“While we are investigating this as a matter of urgency, we can immediately confirm that this communication does not in any way reflect our culture or our equitable employment policies and practices," the spokesperson said.
“We are very proud of our company culture and in particular our multicultural, diverse and inclusive workplace.”
Darren*, a long-time Ribs & Burgers employee, said he was “shocked” to read the memo along with other restaurant staff.
"How does banning staff from speaking their native languages with each other fit in with the culture of #togetherness," he said, adding that workers don't communicate with customers in any language other than English, but may sometimes speak to each other in their native language.
Darren estimates that the majority of the chain’s staff members come from multicultural and linguistically diverse backgrounds.
"We thought the memo was weird but there's nothing we could do about it for fear of repercussions,” he said.
He affirmed that he has spoken with other staff members about the directions to prevent people from speaking their native languages.
'Everyone has the right to speak their native tongue'
According to Fair Work Australia, unlawful work discrimination is defined as when an employer "takes adverse action" against an employee based on race, colour, national extraction, or social origin among other criteria.
And while the "disciplinary action" is not defined in the memo, "adverse action" is defined by Fair Work as dismissing an employee and discriminating between one employee and other employees, among others.
United Workers Union National Council Member Gamal Babiker says businesses have an obligation to respect their employees' multicultural, ethnically and linguistically diverse backgrounds.
This type of discrimination is extremely dangerous and shows a lack of respect for multicultural Australia.
"Everyone has the right to speak their native tongue."
Mr Babiker believes, “It can be an asset for your company when an employee can understand something better if explained by a colleague in their language."
"I could understand the policy if they were speaking to customers in languages other than English, but amongst themselves is a protected right.
"I used to work in a cleaning company, and they picked representatives from every language spoken by the employees, namely Arabic, Greek and Malaysian, to better communicate with each group on behalf of the company.
"At United Workers Union we deliver messages in multiple languages and no one is ashamed of our multicultural and linguistically diverse backgrounds."
SBS Arabic24 has reached out to the restaurant's media team for further comment.
*Not his real name.