Rex Tillerson raised concerns about Iran as a "state sponsor of terrorism"
US accuses Iran of 'alarming provocations'
US Secretary of State Rex Tillerson has accused Iran of "alarming ongoing provocations" aimed at destabilising the Middle East and undermining America's interests in the region.
"An unchecked Iran has the potential to travel the same path as North Korea and to take the world along with it," Mr Tillerson said.
President Donald Trump earlier ordered a review of the Iran nuclear deal.
However, the US admits that Tehran is complying with the 2015 agreement.
Iran has so far made no public comments on the latest developments.
Iran has repeatedly denied accusations by the West that it was ever trying to develop nuclear weapons.
On Tuesday, Washington accused North Korea of trying to "provoke something", after Pyongyang conducted a failed missile test over the weekend.
In response, North Korea said it may test missiles on a weekly basis, and warned of "all-out war" if the US takes military action.
Speaking on Wednesday, Mr Tillerson said the Iran review, which he announced in a letter to Congress a day earlier, would not only look at Tehran's compliance with the nuclear deal but also its actions in the Middle East.
Mr Tillerson accused Iran of undermining US interests in Lebanon, Iraq, Syria and Yemen.
"A comprehensive Iran policy requires we address all of the threats posed by Iran, and it is clear there are many," he said.
The secretary of state earlier acknowledged the Iranians had met the terms of the 2015 deal, but raised concerns about the country as a "state sponsor of terrorism".
President Trump has described the landmark agreement as the "worst deal ever".
However, his predecessor Barack Obama argued the deal, between Iran and six world powers including China, Russia and the UK, was the best way to prevent Iran getting a nuclear weapon.
Sanctions were lifted after the International Atomic Energy Agency (IAEA) certified Tehran had restricted its sensitive nuclear activities.