Air defense systems were activated Thursday evening in parts of Tehran following reports of suspected hostile aerial activity, Iranian state media said, in the first such development since a cease-fire began.

The IRNA state news agency said the "sound of air defence firing" was heard in western Tehran, while the Mehr news agency reported that the systems were activated in several parts of the capital to counter "hostile targets," without elaborating further.

An Israeli security source told AFP that the country was not carrying out airstrikes in Iran, following reports in Iranian state media of blasts over the capital Tehran.

"Israel is not attacking in Iran," the source said on condition of anonymity.

Earlier on Thursday, Defence Minister Israel Katz said Israel was "prepared to resume the war against Iran", adding that his country was awaiting a green light from the United States to return Iran to "the Stone Age."