The French leader, who wants to help lead the EU, invoked the specter of a Europe "where some kind of civil war emerges, where our differences, our national egoisms, sometimes seem more important than what's uniting us."
Democracy has the "best chance" of fighting nationalism, he told members of the Strasbourg-based European Parliament. "Faced with authoritarianism, the answer is not democratic authoritarianism, but the authority of democracy."
European Commission President Jean-Claude Juncker said Macron's rise to power in France has "given new hope" to the European Union. But Juncker stressed that the world's biggest trading bloc isn't a club led by France and Germany. "Europe is an ensemble," even with Britain set to leave the EU next year, he said.
During Macron's speech, some European lawmakers raised placards reading "Stop the war in Syria" and "Hands off Syria" to protest joint airstrikes Saturday by U.S., Britain and France on chemical weapons facilities in Syria.
Countering critics of the airstrikes, Macron showed signs of anger. "(We) are outraged each time by images we've seen of children, women who died of a chlorine attack," he said, almost shouting. "Do we sit back? Do we defend rights by saying: rights are for us, principles are for us, and realities are for other? No! No!"
He said the U.S., France and Britain intervened in a "legitimate, multilateral framework" and stressed that the airstrikes specifically targeted three Syrian chemical weapon facilities "without any human life loss."
On the topic of the EU itself, he told the lawmakers that it's important "to have a democratic, critical debate on what Europe is about." Macron said citizens "want a new project" for the EU that addresses their concerns and fears at a time when allies such as the U.S. are turning their backs on multilateral trade and climate change pacts.
All EU countries, except Britain and Hungary, have agreed to seek the opinions of their citizens on the EU's future through debates and online consultations by summer. Macron called for an energetic campaign for the European Parliament election in May 2019, two months after Britain's scheduled departure from the EU.
However, he ruled out enlarging the EU until the existing members are more deeply integrated and the bloc has undergone reforms. He said now wasn't the time to allow Western Balkans countries to join.
Macron will meet with German Chancellor Angela Merkel in Berlin on Thursday, as France and Germany aim to agree on proposals for EU reforms by June. Macron will attend a debate on Europe in the eastern French town of Epinal later Tuesday.
Sylvie Corbet reported from Paris. Lorne Cook contributed from Brussels.