The US President said in a cabinet meeting on Monday: “We’ll see what phase two is. It might be a total termination. That’s a very real possibility.
“I’m tired of being taken advantage of as a nation.”
Donald Trump called Iranian leaders “great negotiators” who “negotiated a great deal for themselves, but a horrible deal for the US”.
He added: “We’ll see what happens.”
The President decided not to certify the 2015 nuclear deal on Friday, which does not formally terminate the agreement struck by Barack Obama and world powers including Britain, Russia, France, Germany and China.
The move immediately triggered an outcry from other signatories.
On Monday, French foreign minister Jean-Yves Le Drian said he hoped “that Congress does not put this accord in jeopardy”.
Iran responded by saying the move was a direct insult to Tehran and the United Nations.
The speaker for the Islamic Consultative Assembly, Ali Larijani, said: “It seems that Mr Trump not only does not adhere to international agreements, but does not feel respect for the UN and demonstrates to all countries that the US government will not adhere to any obligations.
“Iran openly announced that the nuclear weapons have no place in our military doctrine.
“It seems that Mr Trump because of his hostility with Mr Obama would like to destroy the agreement because of internal issues in his own country.”
US ambassador to the UN Nikki Haley said: “It sends the perfect message to North Korea, which is we’re not going to engage in a bad deal.”
The 2015 Iran deal was design to curb the country’s nuclear programme in exchange for a easing of sanctions.
Ms Haley said the US needs to weigh a response to Tehran’s ballistic missile test, foreign arm sales and sponsoring of terrorism.
On Friday, Mr Trump said: “History has shown that the longer we ignore a threat the more dangerous it become.”
He described Iran as a “rogue regime” responsible for “hostile actions”.
Mr Trump said Iran will “never – and I mean never” achieve nuclear status.
He said Iran was “the world’s leading state sponsor of terrorism” and linked them to the Taliban, Hezbollah and Hamas.