Mahsa Amini, 22, fell into a coma and died following her arrest in Tehran last week by the morality police, sparking demonstrations.
Iranian police have said the death of a young woman in custody was an "unfortunate incident" which they do not want to see repeated, a semi-official news agency has reported.
"This incident was unfortunate for us and we wish to never witness such incidents," Greater Tehran Police Commander Hossein Rahimi said on Monday in a statement reported by the Fars news agency.
He said Mahsa Amini, 22, suffered no mistreatment, denying claims aired on social media against the morality police, who enforce strict rules requiring women to cover their hair and wear loose fitting clothes.
"Cowardly accusations have been levelled against the Iranian police. We will wait until the day of judgment but we cannot stop doing security work," Rahimi said, adding that the morality police was "doing positive work".
He said he could not comment on the cause of death because this was a medical rather than a security issue.
The case of Amini, who was detained last Tuesday after Iran’s so-called “morality police” found fault with her headscarf, or hijab, has set off a public outcry in the country, mainly on social media.
Police said at the weekend Amini fell ill as she waited with other detained women. But Amini's father told Emtedad news website on Sunday that his daughter was fit and had no health problems.
Iran’s judiciary has launched an investigation into the case.
Amini was buried on Saturday in her home city of Saqez in western Iran. Protests erupted there after her funeral and police also then fired tear gas to disperse the demonstrators.
The Fars news agency reported late on Sunday that police arrested several people from about 500 protesters who had gathered on Sunday at Azadi Square in the city of Sanandaj.
Fars said the protesters smashed car windows and set fire to street garbage cans. The agency’s website carried a brief video showing scores of men and women protesting, claiming the police's explanation about Amini's death was “not reasonable."