Madrid confirm Chelsea tried for Aguero last summer
Atletico have suffered a poor start to the Liga season and they now concede they were unable to strengthen their squad after shunning the interest in their key players.
"Madrid's president [Florentino Perez ] told us he would not meet Forlan's buy-out clause because he did not want a public confrontation between the club.
"They hoped we would accept their first offer and in a deal that would have included us having the pick of a number of players, one of whom was Alvaro Negredo."
Gil Marin was asked if Atletico do not sell in the winter transfer window, then would they be forced to listen to offers in the summer if they were not in the Champions League again.
"It will not be a must, but it is obvious that there are cycles with teams and with players," he replied.
"If any player wants to look for a new challenge then Atletico would evaluate it.