He says he did so after attending a family gathering and finding distressed relatives of the woman planning to march to the station.
"I said, 'I just don't think you should be marching on the police station because the police will be doing their job in the proper way'."
Mr Goff said his intervention eased family concerns over whether the woman had an interpreter and a lawyer - and when they would discover her fate.
The woman, 31, and a man, 28, have since been charged with the murder of Davender Singh, 35, who was found stabbed to death in Papatoetoe just over a week ago.
MPs' contact with police became politically charged this year with the resignation of Government minister Maurice Williamson, who called police to inquire into charges against a National Party donor for whom he had lobbied to get citizenship.
Mr Goff said the visit came after a request from a Labour Party member to visit the gathering following the death of Mr Singh. On arriving at the gathering, at which National MP Kanwaljit Bakshi was also present, he found a large group of people upset at the police detention of a woman they knew.
A police sergeant was unable to answer questions, he said. "The group was thinking of launching a protest outside the police station. I said, 'I don't think that's a good idea'."
He said there were minority communities with experience in their own countries which gave them less faith in police in New Zealand than others might have.
Mr Goff said he volunteered to find out what the situation was, particularly in relation to the family's concern the woman had an interpreter or lawyer if needed.
"It was basically to ask the question if she was free to come, if she had legal advice, if she had an interpreter."
He said he spoke to a senior officer, telling him he respected "constabulary independence" and "I don't want to interfere" but that people concerned about the woman were seeking information.
He was told she had a meal, an interpreter, that police were questioning another person and expected to give an answer to the family by the end of the night. He said the information was passed on to the family, which eased concerns they had.
He said it was a "constructive" rather than improper intervention.
"I was able to settle down a situation that was incredibly tense ... It was, I think, helpful to both the family and friends and police it was resolved in that way."
Mr Bakshi confirmed he arrived as Mr Goff was leaving for the police station and entered the property to find those at the gathering were "confused".
He said Mr Goff returned to say the woman had an interpreter and a lawyer. "They were satisfied with that. It was quite an emotional situation."
Mr Bakshi said he would not comment on Mr Goff's actions but would himself use "proper channels" to seek answers for people.
Superintendent John Tims confirmed the visit. "He had a short conversation with a senior police officer and left the police station shortly thereafter. He was making inquiries on behalf of her family who had concerns regarding her welfare and were unaware that she was a person of interest at that stage."
Police Association president Greg O'Connor said it appeared Mr Goff had acted in a way "most New Zealanders would find reasonable".
- David Fisher of NZ Herald
