(CNN) Their first meeting in Brussels was symbolized by a prolonged, white-knuckle handshake -- and months later it appears French President Emmanuel Macron and US President Donald Trump continue to have forceful exchanges.

Macron shed light Sunday on his "very direct relationship" with Trump, telling the BBC's "The Andrew Marr Show" that the two leaders talk "very regularly."

"I'm always extremely direct and frank. He is. Sometimes I manage to convince him, and sometimes I fail," Macron said on the British talk show.

Macron added that Trump was "not a classical politician" and was "elected by his humoring people."

Paris agreement: 'no renegotiation'

Macron, who was elected in May last year, said the two leaders had "built a very strong relationship." However they also disagreed on several topics, including the Paris agreement on climate change, from which Trump plans to withdraw unless the terms are renegotiated.

Macron said the US could only choose between signing or not signing the treaty, adding "we will not renegotiate for one people."

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"I do believe that's a big mistake, I told him but there is no new negotiation. You join or you don't join. China decided to, to remain in the loop," Macron said.

The Paris agreement pushes signatories to reduce their carbon output and hold global warming below two degrees Celsius by the end of the century.

As things stand, the US will be the only country in the world not signed on to the accord when it completes the lengthy withdrawal process in 2020.

'It's not a word you can use'

Macron also criticized Trump's alleged use of the word "shitholes" to describe certain countries while discussing immigration with lawmakers earlier this month.

"It's not a word you can use," said Macron about Trump's reported comment, adding "we have to respect all the countries."

"I think a lot of our issues in both the Middle East and in Africa is due to a lot of frustrations due to a lot of past humiliations," Macron said.

When asked about his opinion on Trump's tweets, Macron replied that people shouldn't "overplay the situation," saying the tweets are a "mix between personal and political reaction."

Macron: Trump's interpreter in Europe?

Macron is one in a small club of leaders with less experience in office than Trump. The 40-year-old French President appears to have used that to his advantage, forging strong ties with the White House based on a mutual desire to change the status quo.

Since their first eye-catching handshake in Brussels, there have been highs (an intimate dinner with wives on the second landing of the Eiffel Tower) and lows (Macron has openly aired his disagreements with Trump on Iran, climate change and the Middle East.)

Through it all, Macron's aides say he views himself as Trump's interpreter in Europe, sifting through the brash pronouncements to find places of common interest.

And as leaders in Berlin and London find themselves distracted by internal politics, including coalition negotiations and Brexit, Paris-Washington ties are enjoying renewed strength.