Washington (AFP) - US President Donald Trump and his French counterpart pledged Saturday to work to denuclearize North Korea, but Trump again invoked the grim possibility of "military measures" if other steps should fail.

Trump's latest warning came amid a flurry of international calls -- from China, the North's key ally, as well as Russia, Germany, Britain and the United Nations -- for the president to show greater rhetorical restraint.

A White House statement said Trump and French President Emmanuel Macron, speaking by phone, had discussed "the increasingly dangerous situation associated with North Korea's destabilizing and escalatory behavior."

It added that the United States and allies were ready "to apply the full range of diplomatic, economic and military measures" to end any threat.

But Macron, while expressing "concern at the ballistic and nuclear threat" from North Korea, said world leaders needed to get Pyongyang to "resume the path of dialogue without conditions," joining the international voices urging caution.

Trump's call with Macron came hours after Chinese leader Xi Jinping had urged the American president in a separate phone call to avoid inflammatory rhetoric toward Pyongyang.

The Chinese foreign ministry said Xi urged Trump to avoid "words and deeds" that would "exacerbate" the already tense situation and to seek a political settlement.

- 'Fire and fury' -

Trump raised alarm around the world -- and particularly in Asia -- by warning that North Korea would face "fire and fury like the world has never seen" if it were to keep threatening the United States.

That drew a sharp rebuttal from Pyongyang, which threatened to launch missiles toward Guam, a US territory in the western Pacific where some 6,000 American troops are based.

Xi's plea for caution came hours after Trump stepped up his earlier warning to Pyongyang, saying the isolated regime would "truly regret" taking any hostile action against the United States.

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The White House said in a statement that the Trump and Xi "agreed North Korea must stop provocative and escalatory behavior" and that both are committed to Korean denuclearization.

Trump has been engaged all week in verbal sparring with the North over its weapons and missile programs, as US media reported Pyongyang has successfully miniaturized a nuclear warhead.

The Republican billionaire has progressively ramped up his tone, declaring Friday that the US military is "locked and loaded."

A commentary in the North Korean state-run newspaper Minju Joson called the warnings from Trump and "other riffraff of the US... the last-ditch efforts and hysteric fit of those who are in the grip of despair" over the "tragic doom" of the "American empire."

In a call with Guam Governor Eddie Calvo on Friday, Trump said the US military is prepared to "ensure the safety and security of the people of Guam."

Japanese media said Tokyo was deploying its Patriot missile defense system following Pyongyang's threat to fire ballistic missiles over the country toward Guam.

- 'Locked and loaded' -

In another move that could fan the flames, satellite photos posted by defense expert Joseph Bermudez suggested North Korea could be preparing for fresh submarine-based ballistic missile tests.

Previously accused by Trump of not doing enough to rein in the authoritarian regime, China last weekend voted in favor of a series of sweeping UN Security Council sanctions against North Korea.

Trump is expected to visit China later this year.

The saber-rattling has sparked worldwide concerns that a miscalculation by either side could trigger a catastrophic conflict on the Korean Peninsula.

Seoul expressed appreciation for Xi and Trump's phone call Saturday.

"We hope today's phone conversation between the two leaders will provide a momentum to defuse the highest-ever tension and to shift into a new phase of resolving the issue," said a statement from President Moon Jae-in's office.

- Moscow 'alarmed' -

Russia's Foreign Minister Sergei Lavrov said Moscow was "very alarmed" at Trump's tough talk, and said Washington should take the first step toward cooling tensions.

"When a fight has nearly broken out, the first step away from the dangerous threshold should be taken by the side that is stronger and smarter," Lavrov said.

German Chancellor Angela Merkel said diplomacy was the answer.

"Germany will very intensively take part in the options for resolution that are not military but I consider a verbal escalation to be the wrong response," she said.

UN Secretary-General Antonio Guterres has called for a lowering of tensions, which tend to increase when Seoul and Washington launch major military joint exercises. The next one is set to begin around August 21.

Relations between Washington and Pyongyang have been tense for months, in the wake of the North's repeated missile tests, including two successful intercontinental ballistic missile (ICBM) test launches in July that are believed to have brought much of the US mainland within range.