The Spaniard has been tipped as one of the potential successors to Luis Enrique, who will quit at the end of this season.
Guardiola managed Barcelona between 2008 and 2012, overseeing one of the most successful periods in the club’s history.
“Never again,” he said when asked about a potential return. “My period at Barcelona is over.”
Guardiola was speaking ahead of City’s Champions League last-16 second leg tie against Monaco. The Premier League side hold a 5-3 lead ahead of the game in France.
“It would be a huge mistake to think about what we have done and forget about what we have to do,” Guardiola said.
“I want to see my team from the first minute want to win the game. We have to score goals.
“Monaco are a fantastic team. I invite the people to come here and they will see a good game tomorrow.
“The best way (to defend) is score goals. When one team scores that many goals and you think about just defending, you kill yourself.
“The idea is to try and attack. We scored five goals when it’s not easy to score against them.”
Guardiola added: “I am not thinking about being in the semi-finals seven times in a row. I am here to help Manchester City reach the next round.
“What I want is tomorrow to make a good game. I want to be in the quarter-finals, it would be a dream for me.”