The Sweden international is unsure as to whether he will greet his former coach, and has stressed the Italian club need to be perfect against the Champions League holders
The Sweden international had a troublesome relationship with the Barca boss during his spell at Camp Nou in 2009-10, and much has already been said about the duo's imminent meeting at San Siro.
"Whether I will shake Guardiola's hand tomorrow? I don't know. What has happened, has happened. Do Guardiola and I still have problems with each other? He has his problems and I have mine. The past is the past," Ibrahimovic stated during the pre-match press conference.
"[Former Barcelona president Joan] Laporta said that they made a mistake when they signed me? That's not what he said before he signed me."
The striker then went on to discuss Wednesday's game, and stressed that Milan would have to be at their best in order to get a good result against the Catalans.
"I know myself and my qualities, as well as the qualities of my team-mates. I'm not worried and neither are my team-mates. The whole team has to play a perfect match, including myself.
"We are playing against the best team, but we have nothing to lose. We have to play two perfect games, because Barca are the best team in the world. They have demonstrated that over the past five years.
"Messi and Barca would also do well if they played in Serie A. No other team in the world has that much quality. Not even Real Madrid. Messi is a formidable player. He's evolving and he's beating all the records. I hope that he will continue like this."
Ibrahimovic also discussed the differences between Spanish and Italian football and feels Serie A is still one of the best leagues in the world, before adding that he's very happy with life in Italy.
"There's more elegance and technique in Spain, but Serie A remains one of the best leagues in the world. It's much more difficult for a striker to play in Italy than in Spain.
"I like the Italians and the Italian mentality. My family like it here and we want to stay. My kids are even more Italian than me."
Wednesday's match kicks off at 20.45 CET.