NEW YORK (Dispatches) -- Iranian President Hassan Rouhani said Monday that America will pay a "high cost" if U.S. President Donald Trump makes good on his threats to scrap the Iran nuclear deal.
Speaking in an exclusive interview with CNN here Rouhani said: "Exiting such an agreement would carry a high cost for the United States of America, and I do not believe Americans would be willing to pay such a high cost for something that will be useless for them."
Rouhani said such an action by the Trump administration "will yield no results for the United States but at the same time it will generally decrease and cut away and chip away at international trust placed in the Unites States of America."
The U.S. extended sanctions relief for Iran last week as part of the 2015 nuclear agreement, which Trump has described as "the worst deal ever."
It was mainly a procedural move, but it was significant, as re-imposing nuclear-related sanctions could lead to Iran reverting back to rapid uranium enrichment -- something Iran has threatened to do if the U.S. reneges on its end of this bargain.
The next major deadline comes in October, when Trump will decide whether to certify that Iran is complying with the agreement, known as the Joint Comprehensive Plan of Action (JCPOA). If he does not, Congress has 60 days to decide whether to reimpose sanctions waived under the deal.
Rouhani said Iran was ready to respond to the possibility of Trump walking away from the agreement.
"Given that Mr. Trump's actions and reactions and policies are somewhat unpredictable, we have thought long and hard about our reactions," he said.
He said any riposte from Iran would come "quite swiftly" and "probably within a week," adding that "if the U.S. wants to increase the tensions it will see the reaction from Iran."
Rouhani, who was reelected to a second presidential term earlier this year, was a key architect of the 2015 nuclear agreement with the United States, the European Union and other partners.
The agreement is expected to feature high on the agenda at this week's UN General Assembly in New York, which both Rouhani and Trump are attending.
On Thursday, Trump again attacked the agreement, calling it "one of the worst deals I have ever seen."
"You'll see what I'm going to be doing very shortly in October," Trump told reporters aboard Air Force One. "But I will say this, the Iran deal is one of the worst deals I've ever seen, certainly at a minimum the spirit of the deal is just atrociously kept. But the Iran deal is not a fair deal to this country. It's a deal that should have never ever been made. And you'll see what we're doing in a couple of weeks."
Trump promised the U.S. is "not going to stand for what they (Iran) are doing," claiming Iran has "violated so many different elements" of the deal.
He promised his upcoming action on the deal in October would be "very evident."
In the meantime, the International Atomic Energy Agency says Iran is complying with its commitments under the deal, including inspections.
Rouhani warned of the diplomatic precedent that would be set by pulling out of the Iran agreement, especially with regard to North Korea.
"I think what the Iranian experience shows is a good experience that can be replicated elsewhere and executed elsewhere," he said.
"But keep in mind please that if the United States wishes to withdraw from the JCPOA, why would the North Koreans waste their time in order to sit around the table of dialogue with the United States, because they would think perhaps after years of talks and a potential agreement the next U.S. administration could step over or pull out of the agreement."
EU foreign policy chief Federica Mogherini also said the nuclear agreement belongs to the entire world, not just the United States.
"I have said many times that the agreement is working fine, and the IAEA has confirmed several times that Iran is fulfilling its obligations,” Mogherini said on Monday.
Commenting on the possible U.S. withdrawal from the nuclear deal, she said the agreement was not signed with one country. "This deal belongs to the international community,” the top EU diplomat said.
French President Emmanuel Macron also said Paris was committed to and supported the JCPOA.
In his meeting with Rouhani, the French president called for the full implementation of the JCPOA, saying any renegotiation of the agreement would be "meaningless.”
Rouhani also met his Austrian counterpart, Alexander Van der Bellen who urged the reinforcement of Tehran-Vienna cooperation in all fields.
UN chief Antَnio Guterres also met with Rouhani and stressed the need for the full implementation of the nuclear deal.
Guterres further said the UN wished for closer cooperation with Tehran towards diplomatically solving regional countries issues.
Rouhani called on the global body to do its best to implement the World Against Violence and Extremism (WAVE) resolution.
"Iran has engaged in valuable operations against terrorism in the region. Political solutions must be sought for regional problems,” he said.         
Rouhani also highlighted the importance of supporting Iraq’s constitution and territorial integrity while stressing the dangers of the upcoming referendum in Iraq's Kurdistan region.
On the war in Syria, Rouhani described Tehran's intervention as a success.
"Our actions were successful and today we are witnessing the final stages of the defeat of Daesh" he told CNN, before calling for eventual elections in Syria.
"The future of Syria will be determined by talks and ultimately the opposition must reach an agreement with the government and the will of people would be the ballot box should ultimately determine what happens," Rouhani told CNN.
CNN also asked Rouhani about Iran's position regarding the current crisis in Myanmar, where the government has been accused by the UN of ethnically cleansing Rohingya Muslims.  
Rouhani said that Myanmar should be condemned and that aid should be forwarded to Bangladesh, where hundreds of thousands of Rohingya refugees have fled in recent weeks.
He also said he shared concerns that Daesh and Al-Qaeda terrorists in Syria and Iraq could move across to Bangladesh and Myanmar to exploit the Rohingya crisis.