Iranian President Ebrahim Raisi said on Thursday that "acts of chaos" are not acceptable, in a warning to protesters who have taken to the streets across the country in fury over the death of a woman in the morality police's custody.

Speaking at a news conference on the sidelines of the United Nations General Assembly in New York, Raisi added he had ordered an investigation into the case of Mahsa Amini, 22, who died last week after being arrested for wearing "unsuitable attire."

"There is freedom of expression in Iran ... but acts of chaos are unacceptable," said Raisi, who is facing the biggest protests in the Islamic Republic since 2019.