French President Emmanuel Macron stood firm Tuesday that landmark agreements on Iran and climate change would not change as he gently nudged Donald Trump to return to the fold.

Macron, like the US president, was appearing for the first time at the annual United Nations gathering of world leaders, but struck a different tone.

Trump devoted much of his own address at the General Assembly denouncing Iran, calling the seven-nation agreement on Tehran's nuclear program championed by his predecessor Barack Obama an “embarrassment to the United States.”

But Macron said that the 2015 deal — reached between Tehran and the five permanent members of the UN Security Council plus Germany — was a “solid, robust agreement that verifies that Iran will not build a nuclear weapon.”

“To reject it now without proposing anything else would be a grave error, and not respecting it would be irresponsible,” Macron told the assembly.

He acknowledged concerns that the agreement does not cover activities after 2025 or touch on other Western and regional concerns about Iran such as its ballistic missile program.

He called for diplomacy to address the issues, saying: “Let's be stricter, but let's not unravel agreements that have already brought security.”

UN inspectors say that Iran is complying with the agreement including its restrictions on uranium enrichment.

But US law requires the president to certify every 90 days that Iran is in compliance and Trump has signalled he will either not do it when the next deadline arises in mid-October, or will pass the decision to Congress where criticism of Iran is high.

Israeli Prime Minister Benjamin Netanyahu has been a forceful critic of the deal, but inside the negotiations France had been seen as pressing hard on Iran.

No renegotiation of climate accord

Trump triggered a global outcry in June when he announced that the United States will pull out of the Paris climate accord, making the world's largest economy and second largest carbon emitter the only outlieralongside war-torn Syria and Nicaragua, which wanted a stronger deal.

Macron said “the door will be open” for the United States to enter the agreement reached in the French capital but vowed: “This agreement will not be renegotiated.”

With scientists likening worsening storms and droughts to climate change, Macron said that the effects of rising temperatures were inescapable.

“Unraveling this accord would be to destroy a pact between nations and generations,” he said, drawing applause from the assembly.

Under the accord signed by 195 nations, each government sets its own plan to curb carbon emissions and meet a global goal of keeping the rise in temperatures this century within two degrees Celsius (3.6 Fahrenheit) above pre-industrial levels.

“I respect the decision of the United States,” said Macron. “The door will always be open to them. But we will continue, with all of the governments, local administrations, cities, businesses, NGOs and citizens of the world to implement the Paris agreement.”

Trump did not mention the climate change agreement in his address.

In contrast to Trump's “America First” credo, Macron embraced multilateralism and expounded on the crucial role of the United Nations as a global body.

“Multilateralism is the most efficient way to confront global challenges,” he said, adding that it guarantees rule of law and protects citizens from “the law of the strongest.”