Russian Federation and China have also vowed to continue with the deal.
In addition to those diplomatic moves, the foreign ministers of Russian Federation and Germany are holding their own talks Thursday in Moscow with Iran on their agenda.
"All parties should engage constructively to address and resolve issues that have arisen with respect to the JCPOA", the foreign ministry said in a statement.
European plane-maker Airbus says it will abide by renewed us sanctions on Iran but that it could take "some time" to determine the full impact of the American decision on the aviation industry's plans to sell billions of dollars' worth of planes to Iran.
Prime Minister Justin Trudeau has delivered a thinly veiled rebuke to the Trump administration and Israel over their opposition to the Iran nuclear deal, setting the stage for a divisive G7 summit next month.
Merkel said in a speech that Germany remains committed to the agreement and will try to do everything it can to ensure Iran fulfills its future commitments.
But hardliners, who have always been against the 2015 deal, stoked outrage against the U.S. Some staged a mass burning of U.S. flags in the center of Tehran.
"Eventually that deal probably falls apart, the Iranians restart their nuclear program, and then relations are so frayed between the United States and all the countries that we put the original sanctions regime in place".
Nonetheless, it stated the easing of sanctions had allowed the Iranian regime to "proceed its destabilizing actions within the area" and that it supported their resumption.
On Tuesday, the US President announced he will be withdrawing from the "defective" JCPOA, which was signed under Barack Obama's presidency.
"The president said he will now work with our allies to get a better agreement with Iran".
Trump's announcement came despite last-minute European diplomatic activity, including a visit to Washington by British Foreign Secretary Boris Johnson, and a call from French President Emmanuel Macron. Cardin wrote, "I voted against the Iran nuclear deal three years ago because I felt it left certain long-term questions about Iran's enrichment capabilities unanswered". During Hassan Rouhani's visit here earlier this year, a joint statement recorded India's support for the JCPOA, describing it as a "crucial contribution to the non-proliferation framework and global peace, stability and security".
"We express regret over this decision made by the United States", Geng said.
Laying out some facts about the deal, Obama said, "the JCPOA was not just an agreement between my administration and the Iranian government". House Minority Leader Nancy Pelosi, a California Democrat, slammed Trump in a statement, saying this "rash decision isolates America, not Iran".
German Chancellor Angela Merkel says the US withdrawal from the Iran nuclear deal shows Europe will face increasing responsibility to secure peace and seek political solutions to conflicts. "It means we are on a collision course".
Several dozen deputies joined them in shouting "Death to America", a favoured slogan of Iranian conservatives. "And the tensions between us and Tehran are going to go nowhere but up, setting up even greater prospect for conflict in the region".
"I don't think that if [this operation] had not happened that Mr Trump would have changed his mind", said Jacob Nagel, a former national security adviser to Mr Netanyahu who had helped lobby against the nuclear deal. "The deal was not sustainable over time".
Shares in Saudi food producer Savola Group 2050.SE , one of the few Gulf firms with big manufacturing operations in Iran, fell only 2.3 percent on Wednesday and remained up 2.3 percent year-to-date, suggesting investors do not foresee disaster for its Iranian business. "Trump did the equivalent of a mercy killing".
In terms of why, there are two narratives floating around the rejectionist camp that are worth noting (beyond the simple pretence that Iran shouldn't have nuclear weapons).