The interior ministry said in a statement that non-Muslim residents living in the conservative Islamic kingdom must respect the sentiments of fasting Muslims by refraining from eating, drinking or smoking in public places.
Muslims observe fasting from dawn until dusk during Ramadan, Islam's holiest month marking the revelation of the holy Koran to Prophet Mohammad 1,439 years ago.
The interior ministry warned that residents who violate the fasting month during the day time in public will lose their jobs in the oil-rich kingdom and be deported.
Saudi Arabia hosts around 7 million foreign residents, mostly non-Muslims from East Asian countries.
Ramadan is due to begin on Oct. 4 or 5, depending on whether the new moon is seen by the naked eye by any Muslim in the country.