"Consuming tobacco or using hookah pipes are forbidden in coffee houses, traditional eateries, restaurants, cafes, hotels, hostels, parks and all other public places," prosecutor Mehedi Kahe said, semi-official news agency ISNA reported.
Kahe said the ban -- set to be made public in the next few days -- was taken on health grounds and warned that any establishments breaking the rules will be shuttered.
Smoking tobacco in public places, except for in the street, has been officially forbidden in Iran since 2006, but the measure is often violated.
The city of Qom, some 120 kms south of Tehran, is a major Shiite theological centre and one of the most conservative cities in Iran.
According to the latest World Health Organisation figures, some 20 per cent of men and 0.6 per cent of women among Iran's population of 80 million smoke every day.