Smokers are facing action in Greece for the second time in a year as the government tries to abolish the addictive habit in the nation.
New legislation effective from Wednesday bans smoking in all public spaces except casinos and large music halls which have a nine-month extension to June.
Customers who flout the law will be liable to fines from 50 to 500 euros (64 to 640 dollars) while business operators risk tougher penalties of 500 to 10,000 euros and repeat offenders could have their licenses revoked.
"This is matter of public health, not a witch-hunt," Health Minister Mariliza Xenoyannakopoulou told a news conference on Monday, adding that her services sought to cooperate with establishments on the issue.
A similar ban had been imposed by the previous government last July -- the third crackdown in a decade -- but controls loosened after elections were called a few months later.
Laws dating to the 19th century have banned smoking in public offices and shops in Greece but this has not kept generations from lighting up.
Forty percent of Greeks are smokers and go through an average of eight cigarettes per day, Ta Nea daily reported on Monday.
The minister said the fines have been lowered from last year's crackdown.
But the gesture has failed to mollify thousands of restaurant and cafe owners who say the initiative could not have been more badly-timed, scaring away vital business in the midst of a recession and an economic crisis.
"There is no way I'm turning away customers, I need them more than ever," Yiannis Tsakos, the general secretary of the association of restaurants and entertainment establishments, told state television NET.
The Socialist government, which is grappling with a debt crisis and only narrowly avoided bankruptcy earlier this year, had already milked the tobacco sector for funds with tax hikes a few months ago.
The measure led to the closure of hundreds of corner kiosks whose main source of business is cigarettes, according to the kiosk operators' union.