Iranian police warned shopkeepers on Tuesday not to use mannequins without headscarves or which exposed body curves, official news agency IRNA reported.
"Using unusual mannequins exposing the body curves and with the heads without Hijabs (Muslim veil) are prohibited to be used in the shops," Iran's moral security police in charge of Islamic dress codes said in a statement carried by IRNA.
Iranian police have stepped up a crackdown on both women and men, boutiques and small companies which fail to enforce strict religious dress codes since President Mahmoud Ahmadinejad came to office in 2005.
The measures are the latest in a country-wide campaign against Western cultural influences in the Islamic Republic, where strict dress codes are enforced.
"Both showing necktie and bowtie behind the windows ... and (the) selling (of) women's underwear by men are prohibited," said the police statement.
In the past, crackdowns tended to be launched at the start of Iran's hot summers and petered out soon after. But last year they extended into winter and included a drive against tight women's trousers and even men with spiky "Western" hairstyles.
Those who violate dress codes are usually cautioned on a first offence, sometimes after a brief visit to a police station. But they can be detained for longer, taken to court and required to have "guidance classes" after repeat offences.
Dress codes are most often flouted in wealthier, urban areas. Conservative dress is the norm in poorer, rural areas.