SHAFAQNA – The Grand Ayatollah Sistani answered a question about smoking at the place with a “smoking is forbidden” sign.
Question: In some buses and other vehicles is written “smoking is forbidden”, is smoking allowed in such places?
The Grand Ayatollah Sistani: if this case is depending on the implicit condition that the passenger in that vehicle has accepted, and/or such a thing is the governmental rule which after entering the country must be observed, it is necessary to act accordingly and doing the opposite is not allowed.
Source: PERSIAN SHAFAQNA