German airliner Lufthansa is grounding all of its flights to Tehran for now, a spokeswoman said.
The company said it would decide when to resume flights once it was able to assess detailed information.
A Thursday flight from Frankfurt to Tehran operated by Lufthansa turned back after around an hour in the air due to changes made to the security assessment regarding the airspace around Tehran airport, according to the spokeswoman.
Lufthansa had planned to resume flights to Iran that day after a one-day halt to services.
The move was in response to a Ukrainian passenger jet crash, which a number of countries believe may have been shot down by Iran in error.
Similarly, low-cost airline Norwegian Air has joined a string of other carriers that have temporarily ceased flying over Iranian airspace following the crash of a Ukrainian passenger jet shortly after take-off from Tehran on Wednesday.
“As a precautionary measure and due to the uncertain situation in Iran, we are re-routing our Dubai flights until further notice,” an airline spokeswoman tells dpa.
The first two Norwegian flights bound for Dubai were rerouted Wednesday evening: One departed from Stockholm the other from Oslo.