France stepped up efforts to convince US President Donald Trump to continue a nuclear deal with Iran on Monday as world leaders gathered for the UN General Assembly in New York City.

Trump met with French President Emmanuel Macron to discuss the deal as well as other international concerns, including terrorism and security.

The US president said on Monday that he would announce a decision "very soon" about whether the US will remain in the deal, making the remarks during a meeting with Israeli Prime Minister Benjamin Netanyahu.

Read more: Diplomats guarded over Donald Trump's inaugural UN visit

France floats post-2025 Iran talks

Earlier, France's foreign minister raised the possibility of resuming talks to strengthen provisions in the accord after 2025. Certain limits on Iran's uranium enrichment are set to expire that year under the nuclear deal.

"France will try to convince President Trump of the pertinence of this choice [keeping the accord] even if work can be done to complement the accord after 2025," Foreign Minister Jean-Yves Le Drian said prior to Macron's meeting with Trump.

Read more: Iran deal — Donald Trump has Europe concerned

However, Trump made no secret of his opposing views during his talks with Macron, State Department Director of Policy Planning Brian Hook said.

"The president believes that the JCPOA (Joint Comprehensive Plan of Action) is deeply flawed, and he did share his views with President Macron about how he believes the deal is flawed," Hook said. "The president was very candid with him about what he thinks are the shortcomings... He told him that it is under review and that they are taking a hard look at the Oct. 15th decision and more broadly how to fix the Iran deal." 

Trump must decide in October whether Iran has breached the nuclear agreement, with critics fearing he may withdraw from an accord that prevents Tehran from building a nuclear bomb.

France and the US agreed to the landmark deal in 2015, along with Germany, Britain, China and Russia.

Under the deal, Iran has dismantled a nuclear reactor, surrendered much of its enriched uranium and submitted its nuclear sites to UN inspection. In exchange, the US and Europe have lifted some sanctions.

Read more: Donald Trump and the Iran nuclear deal – a crisis in the making

Trump: UN has not reached its full potential

Speaking a day ahead of his maiden speech at the UN General Assembly, Trump urged the 193-nation organization to cut costs and reduce bureaucracy.

He began his comments by saying he had seen "great potential right across the street" from the UN headquarters in New York City, referring to a Trump-branded apartment tower.

Trump thanked the UN for helping his property become "a successful project," but said the US wants a better return on its investment in the UN.

Read more: US cuts funding to UN family planning body

"In recent years, the United Nations has not reached its full potential due to bureaucracy and mismanagement," said Trump, speaking at a US-hosted meeting on reform.

"We are not seeing the results in line with this investment," the president said, criticizing the international body's budget.

UN Secretary-General Antonio Guterres, who sat next to Trump during the meeting, echoed Trump's remarks, saying that a reformed UN needs to focus "more on people and less on process."

On the campaign trail, Trump threatened deep cuts to UN funding, once calling it a "club" for "people to get together, talk and have a good time."

rs/cmk (AP, AFP, Reuters)