Iranian Supreme Leader Ayatollah Ali Khamenei has ordered the military to be placed on high alert.
According to Reuters, this comes after U.S. President Donald Trump's recent threats against Tehran.
The report added that Iran has also issued notices to Turkey, the United Arab Emirates, Bahrain, Qatar, Iraq, and Kuwait, warning that any support for a U.S. attack on Iran, including the use of their airspace or territory by U.S. military forces would be considered an act of hostility.
Iran has also rejected direct negotiations with the U.S. on a nuclear deal but expressed willingness to continue indirect negotiations through Oman, a longtime channel for messages between the rival states.
Trump had, last month, said he had sent a proposal to Khamenei for the talks.
Just last week, the American leader vowed to impose additional duties on Iran within two weeks if the negotiations fall through.
Trump also threatened the Islamic Republic with unprecedented bombing in the event of a complete rejection of the deal.
