Both U.S. President Donald Trump and Prime Minister Justin Trudeau sang the praises of their newly minted trade deal Sunday as the two sat down on the margins of the G7 summit.

The United States-Mexico-Canada Agreement (USMCA), painstakingly negotiated after the mercurial president promised to rip up the existing North American Free Trade deal (NAFTA), is the kind of arrangement other leading democracies are pining for, the prime minister said.

"Quite frankly, around the table there's a number of people wanting to make trade deals with each other," Trudeau said of the Group of Seven meeting, which is this year being held in the French seaside resort of Biarritz.

Trudeau and British Prime Minister Boris Johnson met on the edge of the summit on Saturday and agreed to let officials meet in order to finish hammering a temporary trade deal that will keep commerce flowing for the United Kingdom in the aftermath of its exit from the European Union.

Canadian Prime Minister Justin Trudeau, left, President Donald Trump, French President Emmanuel Macron and German Chancellor Angela Merkel pose during the G7 family photo Sunday, Aug. 25, 2019 in Biarritz. (The Associated Press)

The meeting with Trump was the most important one-on-one session for Trudeau, who is expected to tout the benefits of the re-negotiated agreement in this fall's federal election.

"We have a deal that's good for our workers, good for our citizens, good for the middle class, and that's the kind of thing we need to see more of around the world," he said.

There was no hint of acrimony as the two men posed for the cameras. Last year's G7 in Charlevoix, Que., ended with Trump withdrawing his signature from the final communiqué and firing off angry personal Tweets at Trudeau over a perceived slight.

On Sunday, Trump was determined to portray the deal as a political win for him and again called for Democrats to get in line and help ratify the agreement.

"I think it's a very special agreement," the president said.

"Our farmers love it. The unions love it. The workers love it, manufacturers love it. Everybody likes it. I think most Democrats like it. Hopefully, they'll be put to vote fairly soon."

The meeting happened after G7 leaders officially got down to business and held their first major working session, which was devoted to the global economy.

Watch: Trudeau and Trump at the G7

Prime Minister Justin Trudeau and President Donald Trump met at the G7 today. Here's some of what they had to say. 1:51

Leaders were looking for insight about how far Trump intends to take his trade war with China.

Markets tumbled on Friday as Trump escalated that fight.

Trump promised he will raise existing duties on $250 billion US worth of Chinese goods to 30 per cent on Oct. 1, and will hit an additional $300 billion in Chinese products on Sept. 1.

In addition to Trump, Trudeau and Johnson, the G7 leaders include Japan's Prime Minister Shinzo Abe, German Chancellor Angela Merkel, Italy's acting Prime Minister Giuseppe Conte, French President Emmanuel Macron and European Council President Donald Tusk.

Tackling tensions with Iran

In a surprise turn of events, Iran's top diplomat landed in Biarritz on Sunday, though he didn't meet with U.S. officials while there, a foreign ministry spokesperson said.

A French official said Zarif had held talks for almost 3.5 hours, including 30 minutes with Macron, before he boarded his aircraft to leave at 8 p.m. local time.

The official said the talks had been positive and would continue during the leaders' summit this evening and tomorrow.

However, leaders of G7 nations failed at a summit dinner on Saturday to make progress in persuading Trump to reissue oil sanction waivers, a European diplomat familiar with the discussion said.

John Kirton, director of University of Toronto's G7 advisory group, says inviting Iran to the summit is the first step to cooling tensions in the Persian Gulf and dealing with their nuclear ambitions.

The move shows Macron is highly ambitious and has skill in focusing on a central geopolitical problem, Kirton said.

Zarif had only been known to be travelling in the coming days to Asia as part of his tour to get support for Iran amid the U.S. campaign against it since Trump withdrew America from Tehran's 2015 nuclear deal with world powers.

Mousavi stressed in his tweet that "there will be no meetings or negotiations" with American officials during Zarif's trip.

There have been conflicting reports about the G7 leaders' consensus on how to reach out to Iran.

Trump disputed statements by the French government that the nations agreed to empower Macron to send a message on behalf of the group to Iran.

Asked if he signed onto the message, Trump told reporters, "I haven't discussed that."

The French presidency said earlier Sunday that the leaders of the G7 countries agreed to allow Macron to address a message to Iran in their name and to hold talks with Iranian officials.

Germany's Chancellor Angela Merkel arrives for summit meetings Sunday. (Neil Hall/Reuters)

No details were provided on the message but the French presidency said the goal is to prevent Iran from getting nuclear weapons and avoid further escalating tensions in the Middle East.

Macron later walked back his statement, saying he has no formal mandate to speak for the G7 leaders in delivering a message to Iran, but said he would be able to address the issue in the context of what they agreed to during a dinner.

Trump said during a bilateral meeting with Japan's Shinzo Abe that he's not stopping any leader from talking with Iran, noting Abe's recent outreach. He said: "If they want to talk, they can talk."

Trump said he and Abe discussed the possibility of a trade deal between their two nations.

"It will be a very big deal. It's a major deal with Japan, if it gets done, we'll possibly know by the end of this meeting."

Watch this video to catch up on Day 1 of the summit:

A quick recap of some of the big moments from the beginning of the G7. 2:18

Trump asked to ease off on trade disputes

On Saturday, Tusk called for an end to the trade wars, especially the senseless disputes that have divided G7 nations.

Macron is also said to be pushing Trump to ease off.

Prior to coming to the summit, White House officials said Trump is aiming to convince leaders the U.S. approach of tax cut and less regulation is something they should adopt.

They also said Trump is intent on opening up new avenues for U.S. business in both Canada and Europe.

There has been behind-the-scenes sniping at the French by the Americans, according to multiple U.S. media reports.

Bloomberg quoted American officials as saying they believed Macron was trying to isolate Trump by focusing much of the G7's time on climate change.

Separately, senior Trump administration officials told The New York Times the French were talking more about "niche issues" than economic ones.

Climate activists hold upside down official portraits of French President Emmanuel Macron stolen from town halls throughout France during a march in Bayonne, near Biarritz, as part of the G7 summit Saturday. (Sergio Perez/Reuters)

French protesters cite climate change, labour issues

Critics of Macron are marching near the summit to demand he do more to protect French workers and the planet.

A mix of activists, some wearing yellow vests, carried portraits of Macron as they marched Sunday through the southwest city of Bayonne. Some held the portraits upside down.

The protesters are holding portraits in solidarity with environmental activists who removed official portraits of Macron from town halls around France earlier this year to protest his climate change policies.

Internationally, Macron is a vocal champion of fighting climate change, and has challenged Trump on the issue. At home in France, however, activists accuse him of lagging on promises to wean France from fossil fuels.