In the same tweet, the US president added that anyone, who was doing business with Iran, wouldn't be doing it with the US.
The Iran sanctions have officially been cast. These are the most biting sanctions ever imposed, and in November they ratchet up to yet another level. Anyone doing business with Iran will NOT be doing business with the United States. I am asking for WORLD PEACE, nothing less!— Donald J. Trump (@realDonaldTrump) August 7, 2018
On Monday night, the first wave of US sanctions targeting Iran's acquisition of dollar bank notes, trade in gold and other metals, transactions related to the Iranian rial, and purchases of commercial passenger aircraft entered into force.
The day before, EU foreign policy Chief Federica Mogherini and foreign ministers from the UK, France, and Germany said in a statement that the European Union's Blocking Statute would enter into force on 7 August to protect EU companies doing legitimate business with Iran.
In addition, the US president announced the reinstatement of wide-ranging sanctions on Iran, previously lifted under the agreement in exchange for Tehran maintaining the peaceful nature of its nuclear program. Washington's unilateral move has been opposed by other parties to the nuclear deal.