President Emmanuel Macron named fighting "Islamist terrorism" as his top foreign policy priority on Tuesday, vowing to make France a leading power in an unstable, increasingly polarised world.

In a key speech designed to burnish his foreign policy credentials after a difficult first three months in office, Macron said guaranteeing the security of the French was the "raison d'etre" of the country's diplomacy.

"Providing security for our citizens means that the fight against Islamist terrorism is our first priority," he told some 200 French diplomats gathered in Paris.

"There's no place for naivety, nor for fear of Islam that confuses Islamism and Islamic," the 39-year-old centrist added.

France has suffered a series of terror attacks since 2015 that have claimed more than 230 lives, making it the country worst affected in western Europe.

Its armed forces are in action as part of the US-led international coalition fighting the Islamic State group in Syria and Iraq, while French soldiers are also fighting jihadists in west Africa.

Macron, who took power in May on a promise to boost France's international standing, said he would work with the various powerbrokers in the Middle East -- including arch-rivals Iran and Saudi Arabia -- to try to eradicate the jihadist threat.

"Some have chosen (their camp). It's a mistake. The strength of our diplomacy is to speak to all sides," he said.

- 'No alternative' -

Macron also insisted there was no alternative to the 2015 nuclear deal with Iran, which saw sanctions eased on the Islamic republic in exchange for curbs to its nuclear programme. 

It has been fiercely opposed by US President Donald Trump who has called it a "terrible" deal.

"There is no alternative to the non-proliferation agenda. It enables a constructive and demanding relationship with Iran," Macron said, underlining one of many policy disagreements between Trump and himself.

Macron, whose approval ratings have dived in recent weeks, had won kudos for making a bold start on the international stage.

He used frank language with both Trump and Russian President Vladimir Putin within his first weeks in office, raising human rights with Moscow and speaking out against Trump's decision to withdraw the US from the Paris accord on fighting climate change.

Macron announced that Paris will host a summit to review progress on the historic 2015 climate deal on December 12.

- Venezuela 'dictatorship' -

On Tuesday, Macron singled out Venezuela for condemnation in far stronger terms than his European allies, accusing President Nicolas Maduro of creating a "dictatorship" in the crisis-hit South American country.

"A dictatorship is trying to survive at an unprecedented humanitarian cost," he said, echoing the tough US position on the country.

Last week the White House piled financial pressure on Caracas, restricting access to vital US capital markets. 

Macron also fleshed out his plans for deepening the integration of the European Union, which he placed at the heart of his successful election campaign.

"We should imagine a Europe of several formats: going further with those who want to advance, while not being held back by states which want... to progress slower or not as far," he said.

The approach won swift backing from Belgian Prime Minister Charles Michel and his Luxembourg counterpart Xavier Bettel at a joint press conference.

"I'd prefer to have a two-speed Europe than a Europe on the point of death, a Europe that doesn't move forward," Bettel said.

Macron's proposals include creating a budget for the 19-member eurozone which would be overseen by a finance minister and new parliament -- a major institutional change.

German Chancellor Angela Merkel gave tentative backing to the idea of a finance minister and budget on Tuesday in comments ahead of elections in Germany next month.

Macron's speech came a day after he hosted a mini-summit with African and European leaders aimed at reducing the flow of migrants and refugees into the EU.

He said he would soon travel to Burkina Faso to continue building a new relationship with Africa, "a continent of the future" which "we cannot abandon".