Mamoudou is 22-years-old and is an immigrant from Libya.
He said that when he reached the apartment, he became scared and started shaking.
The boy's mother learned the news of the rescue on Reunion Island - the French Indian Ocean territory where she and the father were born and where she still lives.
Malian migrant Mamoudou Gassama is being made a French citizen after being filmed hauling himself up four floors to save a four-year-old child, who he spotted dangling from the balcony in Paris. He will be sentenced in September, according to Bruno Badre, a spokesman for the Paris prosecutor.
The boy was placed in temporary care while the father was in custody, but the two have since been reunited.
Le Parisien newspaper reported that Gassama just happened to be walking by when he noticed the commotion and chose to take action. I like children. I would have hated to see him get hurt in front of me.
Gassama told Macron that God "helped me", during the rescue.
Video captured Gassama leaping into action, scaling the building's facade amid cheers from the gathered crowd before making his way to the balcony where neighbors were struggling to pull the child to safety.
A Malian migrant has been hailed as a national hero in France after he scaled four floors of a building to rescue a dangling toddler.
Gassama told Macron he tried to cross the Mediterranean in March 2014 to reach Italy, but was caught by police. His only concern was for the child, he said. "I ran across the road to go and save him".
Lawyers said the man left his child in the house after going out to the shops, but returned later than he had originally planned after getting distracted while playing Pokemon Go.
President Emmanuel Macron met with 22-year-old Mamoudou Gassama on Monday to thank him personally after videos capturing the spectacular rescue went viral on social media over the weekend.
Macron is behind a bill toughening French immigration law, and he stressed there is no contradiction between rewarding Gassama for his act of bravery and working to prevent migrants from entering France illegally by stopping the stream of arrivals at its source.
From there he continued on previous year to France, where he joined relatives in the eastern Paris suburb of Montreuil, nicknamed "Little Bamako" after its large Malian population.