Despite losing 2-1 to Barca at home, Atletico won the tie 3-2 on aggregate.
Alemany left Barca last year ahead of joining Atletico and said: "The first thing I want to highlight is how the 70,000 Atlético fans carried us on their shoulders and the team's attitude, which is as it always is.
"Our coach (Diego Simeone) always gets the best out of them. I liked the team's reaction after going down 0-2, and we deserved to be in the semi-finals."
He also said, "I wouldn't like to single out one player. Everyone had their own circumstances. I know how the match was prepared, like a final. We have to acknowledge the high level Barcelona showed.
"Not by much, but we were a little better than Barcelona."
He also took the time to send a message to Barça.
"I wish them the best of luck in La Liga, which they have practically secured. I spent two wonderful years there," he stated.