Aguero and Giannina Maradona, daughter of Diego, split last year, since when she and son Benjamin, who was born in Madrid, have returned to Argentina.
Aguero told Argentina newspaper Ole: "In recent months, I've been trying to adapt to a new stage after my separation. It is not easy because they were very intense years together and they were very strong experiences with Gianni.
"During that time we grew a lot as individuals and as a result of that love, we had Ben. That is a blessing.
"That's what I find most difficult, because Ben is in Buenos Aires and I for obvious reasons am in Manchester."
Asked if he was letting it affect other areas of his life, Aguero added: "I try not to, because you try to be as professional as possible. I don't think it affects my athletic performance, if that's what you mean.
"But being away from a child is not easy. It is impossible for me not to miss Ben."