"We have to protect ourselves with respect to China, Russia and even the United States of America," Macron told Europe 1 radio in an interview recorded at Verdun, the site of a 1916 battle that cost more than 300,000 lives.
Claiming that, after 70 years of peace in Europe, the situation is now "precarious", he warned of "intrusion attempts in cyberspace and numerous interventions in our democracies" - an apparent reference to Russia - as well as the danger of US President Donald Trump's plan to quit a Cold War-era nuclear treaty.
"We will not defend the European people unless we decide to have a real European army," he said.
Macron has spearheaded the creation of a nine-country European force that could mount a joint military operation, evacuate a war zone or provide aid after a natural disaster.
The nine countries' defence ministers were to meet in Paris for the first time on Wednesday.
Macron also condemned "authoritarian powers which are reemerging and rearming within the confines in Europe", repeating his warning against "nationalism that plays on people's fears", as it did in the 1930s.
Le Pen lashes EU "empire"
Far-right leader Marine Le Pen laid into Macron for his criticisms of her cothinkers in Hungary and Italy on Tuesday.
There was a "real paradox" in commemorating the French soldiers who "gave their lives to defend their nation, to defend their borders and at the same time being so aggressive, so violent and hateful towards people who politically, peacefully and democratically want to defend their nation and borders", she told Radio Classique.
The danger of a new war is "completely hypothetical", Le Pen insisted, accusing Macron of defending the "new Empire ... that is the European Union, which crushes the European peoples beneath its boot".
Ultraliberalism and migration
In the interview, Macron acknowledged that there was discontent over an "ultraliberal Europe that doesn't allow the middle classes to live well any more" and promised to answer "fear of migrants" by restricting asylum to "those who need protection" and enforcing "security and protection of our borders".
But "the fact that people have been elected doesn't mean that you can't combat their ideas," he insisted, although "one shouldn't scorn the peoples that have elected them".
Price rises, violence in schools
On Tuesday Macron inaugurated a memorial in Reims to the 200,000 troops from France's colonies who fought in the war after announcing that the French soldiers would be honoured in France's Pantheon along with author Maurice Genevoix.
In Verdun several members of the public took him to task over his government's policies, notably the rises in the CSG tax and taxes on petrol and diesel fuel.
He told them they had probably gained more than they had lost due to the scrapping of housing tax.
Earlier he promised heating grants for people on low incomes and financial assistance for workers who need to use their cars to travel long distances to work.
Responding to uproar over a video of a school student threatening his teacher with an imitation gun, he said that police officers might be posted in schools, if the "education community" agrees to the measure and pledged to carry out a "work of civilisation, educational, moral and security-oriented" in deprived areas.