"That's not what allies do," Macron said in Nuuk, Greenland's capital.

Macron is the first foreign head of state to visit the vast territory -- at the crossroads of the Atlantic and the Arctic -- since Trump's annexation threats.

Since returning to the White House in January, Trump has repeatedly said America needs the strategically located, resource-rich island for security reasons, and has refused to rule out the use of force to secure it.

"Everybody thinks -- in France, in the European Union -- that Greenland is not to be sold, not to be taken," Macron told reporters as he wound up a six-hour visit accompanied by Danish Prime Minister Mette Frederiksen and Greenlandic Prime Minister Jens-Frederik Nielsen.

Speaking at a press conference held outdoors at the Old Port in Nuuk, the French leader said his trip was aimed at conveying France's and the EU's "solidarity" with Greenland.

He stressed the island's "territorial integrity" as dozens of Greenlanders cheered and waved their territory's red-and-white flag.

Denmark has also repeatedly stressed that Greenland "is not for sale".

Macron earlier kicked off his visit with talks on board a Danish frigate with Frederiksen and Nielsen, discussing among other things "the increasing cooperation" between Russia and China in the region, he said.

France was ready to hold joint military exercises with Arctic countries, under the framework of NATO and the NB8 Nordic and Baltic countries, to ensure security in the region, Macron said.

Copenhagen in January announced a $2 billion plan to boost its military presence in the Arctic region.

Macron then visited a glacier to see firsthand the effects of global warming.

His trip to Greenland was "a signal in itself, made at the request of Danish and Greenlandic authorities", his office said ahead of the visit.

- 'Not for sale' -

The Danish invitation to Macron contrasts sharply with the reception granted to US Vice President JD Vance, whose one-day trip to Greenland in March was seen as a provocation by both Nuuk and Copenhagen.

During his visit to the US Pituffik military base, Vance castigated Denmark for not having "done a good job by the people of Greenland", alleging they had neglected security.

The Pituffik base is an essential part of Washington's missile-defence infrastructure, its location putting it on the shortest route for missiles fired from Russia at the United States.

Polls indicate that the vast majority of Greenland's 57,000 inhabitants want to become independent from Denmark -- but do not wish to become part of the United States.

Unlike Denmark, Greenland is not part of the European Union but is on the list of Overseas Territories associated with the bloc.

The Arctic has gained geostrategic importance as the race for rare earths heats up and as melting ice caused by global warming opens up new shipping routes.

Macron said the EU wanted to "accelerate the implementation" of a partnership with Greenland on minerals including strategic metals.

The "strategic partnership" signed in 2023 "must allow us to develop sustainable value chains in the strategic raw materials sector", he told reporters.

The EU has designated as critical raw materials 25 minerals, including rare earths and graphite found in Greenland.

- Mount Nunatarsuaq -

Macron took a helicopter tour of a glacier on Mount Nunatarsuaq, about 30 kilometres (19 miles) from Nuuk, where he was able to observe a sea of fissured ice as far as the eye could see.

The Arctic is warming four times faster than the rest of the planet, according to a 2022 study in scientific journal Nature.

Greenland's ice sheet melted 17 times faster than the historical average during a May 15-21 heatwave, a recent report showed.

Macron also took a walking tour on a rocky, grey stretch of the glacier, until recently covered in ice, a changing landscape which is having a major impact on local communities, the Greenlandic prime minister explained.

Measuring 9,000 square kilometres, the Nuuk fjord system is one of the biggest in the world.

Macron left Greenland Sunday evening to fly on to Canada for a G7 meeting.