The French president, Emmanuel Macron, has warned that Europe can no longer depend on the US for its military defence and called for an urgent new European security policy in the face of rising nationalism and extremism.

“Europe can no longer rely on the United States for its security,” Macron said in a foreign policy speech at what he called a “crisis moment” for European politics and global multilateralism. “It is up to us to guarantee European security.”

Macron vowed to put forward new proposals in the coming months for the EU to boost defence cooperation, as well as talks with Russia on their security relationship, an issue of concern for countries on Europe’s eastern edge.

The pro-European French centrist warned that Europe was only just beginning a long battle to address rising nationalism and that the postwar, western-dominated world order was in danger.

Macron came to power last year by beating France’s far-right candidate Marine Le Pen on a manifesto that involved promising to save the EU by championing a more integrated Europe, styling himself as a leader of progressives against hardline nationalism.

The first major political test for his new centrist movement, La République en Marche, is next spring’s European elections, where he is hoping to prove that the centre ground can limit the rise of far-right parties and Eurosceptics in Europe.

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But Macron conceded that much had changed in the past year. He warned of an “awakening of nationalists and extremes” in Europe and hit out at what he called US president Donald Trump’s “aggressive isolationism”.

Macron’s comments follow Trump’s repeated distancing himself from the Nato military alliance, which groups the US with most of Europe and has underpinned European security since the second world war. “The partner with whom Europe built the new post-world war order appears to be turning its back on this shared history,” he told French ambassadors gathered at the Élysée Palace.

Macron defended his policy of maintaining a close relationship with Trump, who has shunned European allies by pulling out of a global climate pact, imposing extraterritorial sanctions on Iran and imposing tariffs on EU steel and aluminium.

Macron said communication with Washington had to be open and constructive, but European countries had to work together to come up with alternatives to hardline isolationist politics. “The question is not about whether I grab Trump by the arm at the next international summit; the question is, what are we going to reinvent?”

He said moments such as the UK’s Brexit vote, the Trump election or the success of Hungary’s Viktor Orbán were linked to a crisis in modern globalisation and it was now up to countries to overhaul global governance and make globalisation more “human”.

But since Macron vowed last year to overhaul the EU – pushing for deep political reforms, including a separate budget for the eurozone – he has appeared isolated, amid a rise of Eurosceptic and nationalist parties in countries from Italy to Hungary and gains by the far right in Germany.

Macron insisted that France had to push on with EU reforms because “we’re paying the price of several decades of a Europe that has become bland, weakened and hasn’t made enough suggestions”. He added: “Do China and the United States think of Europe as a power with similar independence to their own? It is not the case.”

Macron said France respected the UK’s Brexit vote and wanted to maintain a strong, strategic relationship with London, but he warned he would not allow the move to be to the detriment of EU unity, which was his priority.