The legendary Argentine has revealed that he advised the Santiago Bernabeu side's head coach to sign the attacker before he moved to Manchester City in the summer
Aguero publicly declared his desire to leave Atletico Madrid, and, although he was linked with a move to Real more than once, the transfer never materialised and he eventually joined Manchester City instead.
"Real Madrid need a super team if they are to stop Barcelona and Sergio Aguero would have been the perfect man to help them to the same level as Barca," Maradona was quoted as saying by Marca.
"I have advised Mourinho to sign him more than once, but Real Madrid didn't listen.
"Barcelona now have a huge advantage over Madrid. We will see how everything turns out at the end of the season."
Barcelona currently sit fourth in the Primera Division table with seven points from three games, while Madrid lie sixth with six points.