The woman, an employee at a South Auckland store, alleged that another staff member had pushed, scratched and attempted to bite her during a scuffle at work.
Then in an email from the chain's regional manager, the employee was warned against going to any news media about the incident as it would be a "breach of confidentiality".
Police confirmed it received a complaint relating to a minor assault incident between two parties at the store on February 8.
"Enquiries into this incident are ongoing and there's no further update at this time," a police spokesman said.
The staff member, who didn't want to be named, was not in a mental state to talk, according to her husband.
He provided a medical certificate stating she suffered "contusion to the left of her face, scratch marks on her left upper arm and dorsum of her left wrist".
"She also exhibits significant symptoms of post-traumatic stress disorder with flash backs, nightmares, insomnia and very low mood," the medical document said.
"My wife is very badly affected by the incident and of course it is made worse because of the company's threat against her to talk about it," the husband said.
"I think she feels very let down because instead of getting support and understanding, the company is using a confidentiality clause in her employment contract to try to silence her."
The husband said she had been a victim of bullying at her workplace, which included being spoken to rudely by her seniors in front of customers and also being often scolded for no reason.
The manager wrote in his email to her that the company considered matters relating to the incident as confidential.
"For the avoidance of doubt, MHJ [Michael Hill Jeweller] considers that any disclosure of such confidential information to media outlets would be deemed to be a breach of confidentiality, your individual employment agreement and MHJ's confidentiality policy," he wrote.
When approached, the manager said he could not comment on the matter.
"I cannot comment except to say that Michael Hill takes allegations such as these very seriously, and any such matter would be handled with urgency internally, in line with Michael Hill's policies and procedures," he said.
In an email dated February 17, 2021, to the company, the woman claimed she had been bullied while at work.
"I have been bullied by other employees in Michael Hill for a long time, and I have reported my workplace bullying issue to my manager so many times," she said.
"But no one in the company tries to solve the problem at all. Due to long-term workplace bullying, my physical and mental health is greatly harmed."
She said that as a result of workplace bullying, she has had trouble eating and sleeping.
