More than 1,500 protesters marched between Place de la République and Bastille in eastern Paris, leading to brief clashes with police and dozens of arrests.
The demonstrations came a day after Macron – infamous among trade unions for loosening labour laws – won France’s presidential run-off against far-right candidate Marine Le Pen.
"He needs to cool down," said Raphael Garine, a protesting student. "If he wants to continue the reckless policies of the past five years we will take to the streets to demonstrate."
In the Paris metro, a defaced advertisement captured the mood. "Macron: Not even started, already hated," it read.
Smaller protests were also organised in other French cities, including Nantes, Lyon, Grenoble and Strasbourg.
Scattered groups of masked protesters dodged police firing tear gas only hours after election results on Sunday night in Paris, with officers arresting 141 people.
France's biggest trade unions on Sunday issued warnings over Macron’s victory, with the powerful CGT union calling for an immediate show of force in the streets.
The CFDT, France's biggest union, welcomed Macron's victory in a statement but added that the Le Pen’s score was still too high.
During the presidential campaign, many groups held protests against Le Pen and her right-wing National Front party.
Unions, students march in Paris the day after Macron victory
10 May 2017
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Several hundred people, including union members and students, protested in the streets of Paris on Monday, warning French president-elect Emmanuel Macron they would actively oppose his pro-market reforms.
