By Jim Muir
BBC correspondent in Tehran
Young Iranians have taken to gathering around the qalyoun to smoke and flirt
Iranian officials have said that smoking the hubble-bubble, or water-pipe, will be banned in all restaurants and leisure places from Monday.
The water-pipe is one of the most traditional instruments of relaxation and indulgence in the Middle East.
In Iran, where it is known as the qalyoun, it has been at the centre of traditional culture for centuries.
Fines and confiscation
The sweet scent of fruit-flavoured tobacco wafting around restaurants and teahouses is a familiar part of any scene of public relaxation in Tehran. But not for long - if the authorities have their way.
Police and public health officials will now be out and about making sure that this latest clampdown on public pleasure is fully applied.
Restaurant owners and people caught smoking the qalyoun on their premises or in public places will be liable to fines and confiscation of the offending items.
For a transitional period only, private rooms may be set aside for men only to indulge their habit.
It is not clear quite why this highly popular, traditional and seemingly innocent pastime is being suppressed.
Officially, it is to do with health - but cigarette smoking is still permitted in restaurants and elsewhere - and is generally regarded as much more harmful. With the water-pipe, the smoker does not inhale any tar.
The move comes amid preparations for a broader summer crackdown on what hardline officials here call "social corruption".
This includes poor observance of Islamic dress codes and public morals, parties involving alcohol and the mingling of unmarried people from both sexes.
It is in this context that most people are bound to see the move to oust the hubble-bubble from public sight and scent, especially since young people have recently taken increasingly to gathering around the qalyoun to smoke and flirt.
It remains to be seen how successful the drive will be in such a big country where the practice is so widespread.
Qalyoun vendors complain that their sales have already been plummeting.
But it is not illegal to sell the pipes or to use them at home, so the indulgence is certain at least to be kept alive where most Iranians have their real fun nowadays - behind closed doors.