The PSG striker's move to Real Madrid was confirmed this week.
Mbappe will join Real at the end of the month as a free agent. Minguella, who placed both Diego Maradona and Leo Messi at Barca, recalled to Radio Marca: "My son, who was in France, told me that Monaco was liquidating the team.
"So, I spoke with the parents personally, the boy was 18 years old, and with the departure of Neymar, he told me that it would be a pleasure to go to Barça.
"I told FC Barcelona and they responded that, for the same value, (Ousmane) Dembélé was better off. They thought that, the then Borussia Dortmund player, he was more suited to Barça's way of playing."
He added: "Barça is in a complicated economic situation, there are few miracles in football. Furthermore, Real Madrid, in this second stage of Florentino Pérez, is going very strong. We have to face the difficult moments and turn the situation around."