Trump, it said, "has directed a National Security Council-led interagency revew of the Joint Comprehensive Plan of Action that will evaluate whether suspension of sanctions related to Iran pursuant to the JCPOA is vital to the national security interests of the United States".
Instead, the Trump administration would conduct a "comprehensive review" of USA policy toward Iran, Tillerson said, leaving one of Barack Obama's signature policies in place - for now.
Secretary of State Rex Tillerson said today that the Trump Administration is trying to force North Korean leader Kim Jong Un to the negotiating table.
He accused Iran of supporting terrorism and destabilising the Middle East as the Trump administration launched a review of the Iran nuclear deal.
"It remains a leading state sponsor of terror, through many platforms and methods".
President Donald Trump earlier ordered a review of the Iran nuclear deal.
Tillerson did not say how long the review would take.
Tillerson also appeared to sketch out the terms of such diplomatic engagement, suggesting that the US would not offer aid for concessions from North Korea as has been done in the past.
Another Western diplomat called the administration comments "a politically acceptable way of sending the certification to Congress" that Iran is holding to the deal, describing it as "certification dressed up in rhetoric" of criticism toward Tehran. Tillerson spoke a day after certifying to Congress that Iran is complying with its obligations under the 2015 deal, a requirement for Tehran to continue receiving relief from nuclear sanctions.
The agreement between Iran and six world powers, negotiated during Barack Obama's presidency, placed limitations on Iran's nuclear program in exchange for lifting global oil and financial sanctions against Iran. Critics have said it's unfathomable that the US would grant sanctions relief to Tehran even as it continues testing ballistic missiles, violating human rights and supporting extremist groups elsewhere in the Middle East.
Tillerson said one of the mistakes in the way the agreement was put together was that it ignored all the other serious threats Iran posed outside of its nuclear program.
Trump hasn't given a timeline for when his administration's review of Iran policy - including whether to stick with the deal - will be complete.
Trump has between four and eight years left in office, depending on whether he wins a second term. The April 18 certification was the first by the Trump administration.
And, with a funding deadline looming to keep the government running, Trump said it was possible Congress would manage to accomplish it all next week or "shortly thereafter".
Obama, Kerry and others who negotiated the deal strenuously defended its terms and said the agreement made the world a safer place.
Since the pact was signed, Pompeo said, "The list of Iranian transgressions has increased dramatically".