The 2015 agreement between the United States and Iran also was signed by China, France, Russia, Britain, Germany and the European Union, and these countries would have been unlikely to join the United States in reimposing sanctions.
Iran promised a strong reaction to the sanctions, which it said violate worldwide law and prior U.S. commitments.
Trump earlier in the day said he once again would extend US sanctions relief for Iran, as required under the deal in exchange for curbs on Iran's nuclear activities, but he intends to pull the United States out the agreement unless it is strengthened within months.
Responding to Trump's harsh stance, Iranian Foreign Minister Mohammad Javad Zarif said on Friday that it was "desperate attempts" to undermine an accord which Iran said was "not renegotiable".
In a background briefing, senior administration officials said this is Trump's "waiver" on Iran.
This would not entail negotiations with Iran but would be the result of talks with European allies, the official said.
What is the nuclear deal?
But he has continued to follow the example of his predecessor Barack Obama in regularly signing sanctions waivers so that United States economic measures against Tehran do not "snap back".
Trump had faced a Friday deadline to decide on whether to waive the sanctions.
He further commented on Trump's attempts to prevent the expiration of restrictions on Iran's nuclear activities and said the 15-year period for the limits' expiration is one of the key provisions of the JCPOA and the USA can not violate it.
United Nations inspectors have certified Iran's compliance with the deal nine times, most recently in November. Trump has said that the nuclear deal, which he called the "worst deal in history", was flawed in part because it did not address missile development. "He intends to work with our European partners on some kind of follow-on agreement that enshrines certain triggers that the Iranian regime can not exceed related to ballistic missiles, related to nuclear breakout period ... to inspection and that would have no sunset clause", said an administration official. He accused Iran of "not living up to the spirit" of the agreement even though the International Atomic Energy Agency says Tehran is complying.
The findings, in a report given to the UN Security Council this week, could add weight to American and Saudi efforts to ostracise Iran with accusations that the Iranians are engaged in destabilising behaviour in the Middle East.
USA presidents, under existing American law, must waive the sanctions every few months to prevent them from causing Iran to declare the nuclear pact violated and simply walk away to resume pursuit of an atomic arsenal.