Macron says 'horrified' at UK attack, to speak with May
Children were among those killed, police have said, in what May called an "appalling terrorist attack".
Macron "learnt with horror and shock about the attack that occurred yesterday evening," his office said in a statement.
"He addresses all of France's compassion and concern to the people of Britain and stands by its side in this period of mourning, with a particular thought for the victims and their families," the statement added.
French Prime Minister Edouard Philippe condemned the attack as "the most cowardly terrorism" that was aimed "specifically and knowingly" at young people.
In what is Britain's deadliest terror attack in 12 years, police said a man detonated a bomb at a concert in the northwest English city by US pop star Ariana Grande.
France has been a frequent target of attacks since January 2015 with more than 230 people killed, including 90 in the Bataclan concert hall in Paris during the November 2015 attacks.
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