Air defense systems were heard operating in parts of Tehran on Thursday evening, according to Iranian media.
State news agency IRNA said that the sound of air defenses was heard in both western and eastern areas of the capital.
No further details were immediately available.
Iranian media outlets, however, said later that the activation of the air defenses in Tehran was part of a test.
Meanwhile, an Israeli military source denied any involvement.
"Israel is not attacking Iran," the source told Yedioth Ahronoth newspaper.
