Several hundred people demonstrated in Iran's capital on Saturday to demand that state television boost "the culture of the veil and chastity" in its programming.
Protesters denounced the presence of "badly veiled" women in soap operas and said women wearing the traditional full-body chador were often depicted as poor and uncultivated.
Under Islamic law in force in Iran since the 1979 revolution, women must wear loose clothing and a hijab, a veil covering the hair and neck.
A police "morality" unit is responsible for enforcing the law, and can impose fines or even arrest those who defy it.
But recent years have seen many women wear a thin veil that hardly covers the hair, tight clothing or coats reaching mid-thigh instead of the long coat or chador.
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"The law must be respected if the chastity of society is to be preserved," demonstrator Fatemeh Rahmani told AFP.
Another woman at the gathering, Zeinab Moeini, said: "The morality police arrest women who create problems and 'bad hijab' in Iranian society."
Media reports said similar rallies were staged across the country on Saturday.
In June, 195 of the conservative-dominated parliament's 290 MPs wrote to President Hassan Rouhani asking him to enforce the dress code law, denouncing what they called a Western "cultural invasion".
Rouhani, is a moderate elected in June 2013 after campaigning for greater cultural and social freedoms in the Islamic republic.
In October, he asked police to be moderate when enforcing the hijab requirements.
He has also said that "We cannot take people to heaven by using whips," a remark that was condemned by conservatives.