TEHRAN (Reuters) - The Iranian army shot down an unidentified drone on Friday in the southwestern port of Mahshahr on the Gulf coast, the ISNA news agency reported.

The plane was shot down by the "Marsad" missile defense system over Iranian territory, according to the news agency Tasnim, which is close to the conservatives.

Iranian media did not say whether the aircraft was civilian or military, and Iranian officials could not immediately be reached for comment.

The Army Radio Club of Young Journalists said the army had shot down an "unidentified flying object", adding that officials had not yet confirmed the report.

Relations between Tehran and Washington have deteriorated since US President Donald Trump last year pulled out of a 2015 nuclear deal with Tehran and reimposed sanctions.

In June, Iran shot down a US drone, which the Revolutionary Guards said was flying over the south of the country. Washington said it was in international airspace over the Strait of Hormuz in the Gulf.