The sanctions came after the Iranian Revolutionary Guards dropped an American drone over the Strait of Hormuz a few days ago.
Trump said when he signed the executive order that the severe sanctions targeted the Iranian regime's supreme leader Ali Khamenei, and that his country wants to stop Iran's sponsorship of terrorism.
Trump explained that the new package of sanctions would have been imposed on Iran regardless of the downing of the US drone.
He stressed that the United States will not allow Iran to acquire nuclear weapons, but at the same time said that his country is not seeking war.
Source: Sky News