"Bravo," Macron said to Gassama during a one-on-one meeting in a gilded room of the presidential Elysee Palace that ended with the awarding of a medal from the prefecture for "courage and devotion."
Gassama's feat went viral on social media, where he has been dubbed "Spiderman" for climbing up five floors, from balcony to balcony, and whisking a four-year-old boy to safety Saturday night as a crowd screamed at the foot of the building in Paris' northern 18th district.
The young man said he has papers to legally stay in Italy, where he arrived in Europe after crossing the Mediterranean after a long, rough stay in Libya. But he wants to join his older brother, who has lived in France for decades.
Gassama, dressed in blue jeans and white shirt, recounted his experience which took place at around 8 p.m. Saturday when he and friends saw a young child hanging from a fifth-floor balcony.
"I ran. I crossed the street to save him," he told Macron during a filmed portion of the meeting. He said he didn't think twice. "When I started to climb, it gave me courage to keep climbing."
God "helped me," too, he said. "Thank God I saved him."
Gassama felt fear when he took the child into the apartment. "I was trembling," he told Macron.
"Because this is an exceptional act ... we are obviously, today, going to regularize all your papers," Macron told him, "and if you wish we will start nationalization procedures so you can become French."
Gassama told Macron that he arrived in Italy in 2014 after more than a year in Libya, where he was arrested and beaten, "but I wasn't discouraged."
The French president is toughening the nation's approach to immigration, and stressed that not all who make the treacherous journey to Europe can be welcomed, but that Gassama's actions were admirable.
"You saved a child. Without you, no one knows what would have become of him," the president said. "You need courage and the capability to do that."
Working as a firefighter corresponds with his skills, Macron said, and opened the door for him to join.
"You have become an example because millions have seen you" on social media, the president said.
The French media reported that the father of the small child was detained for alleged parental neglect.