May 6 (UPI) -- Iranian President Hassan Rouhani warned the United States on Sunday it would be a "historic mistake" if it abandons the 2015 nuclear deal.
U.S. President Donald Trump has said he will decide Saturday whether the agreement will be re-certified. Congress requires the president to approve the agreement every three months.
"If America leaves the nuclear deal, this will entail historic regret for it," Rouhani said in a televised speech to a crowd in city of Sabzevarr, northwestern Iran.
He said Iran has "a plan to counter any decision Trump may take and we will confront it."
Rhouhani also said, "When it comes to weapons and defending our country, we will not negotiate with anybody."
Rhouani said Tehran's nuclear program is peaceful, but the nation will build "as many facilities, weapons, missiles that are necessary for our country," and "it is none of others' business."
Trump has described the 2015 agreement, which lifted sanctions on Iran in return for limits on its nuclear program, as "terrible." The agreement was also approved by China, Russia, Germany, France, Britain and the European Union.
France, Britain and Germany have told Trump the current deal is the best way to stop Iran developing nuclear weapons. British Foreign Secretary Boris Johnson on Monday plans to discuss the matter with Vice President Mike Pence, national security adviser John Bolton and foreign policy leaders in Congress.
Trump wants Congress and European powers to fix "disastrous flaws."
U.S. Rep. Mac Thornberry, R-Texas, the chairman of the House Armed Services Committee, said on Fox News Sunday he "would counsel against" Trump pulling the United States out of the deal and instead give Britain and France time to negotiate a stronger accord.
Thornberry said it is a bad deal but if it's scrapped, Iran could kick out inspectors and "we lose what visibility we have there."
Rouhani said only three countries oppose the deal -- the United States, Israel and Saudi Arabia.
Also Sunday, Israeli Prime Minister Benjamin Netanyahu again criticized the agreement during a cabinet meeting, and accused Iran of supplying advanced weapons to the Syrian government.
"We are determined to block Iran's aggression against us even if this means a struggle," he said. "Better now than later."