Iran's top legal authority wants to prosecute organisers of a party arranged by Tehran City Hall commemorating Iranian Women's Day, the semi-official ISNA news agency reported.
A video of Tuesday's event, during which young girls danced in front of a mixed audience in the Iranian capital, was widely broadcast on social media networks and criticised by conservatives.
It shows a group of girls dressed in tight jeans and a type of tutu performing a choreographed dance set to music played by a traditional orchestra and a choir composed mostly of women.
Among the men in attendance at the event largely dominated by women wearing the all-encompassing black chador was Tehran's reformist mayor, Mohammad Ali Najafi.
According to ISNA, Iran's attorney general Mohammad Jafar Montazeri felt the event had included "acts against public morality" and Islamic tradition.
Montazeri ordered Tehran's prosecutor to "quickly examine the issue and launch legal proceedings against those responsible".
Islamic law in Iran prohibits public dancing.
Similarly, women are forbidden from singing in front of men if their voices are not covered by male voices.
Najafi tried Wednesday to disarm critics with a decree demanding that Islamic traditions are respected in ceremonies organised by the town hall.
He also said that one could have "criticisms" for this part of the ceremony, but that it should not be questioned as a whole.
Party organiser Fatemeh Rakeii, the mayor's adviser on women's affairs, said she did not understand critics of a show starring girls under the age of nine.
Iran is not officially celebrating the annual International Women's Day, marked by the United Nations on March 8.
The country celebrates its own women's day on March 9, marking the birthday of Fatima, the Prophet Mohammed's daughter.