UEFA said in a statement that Man City had committed "serious breaches" of the rules while the Premier League club swiftly said they intended to appeal the decision to the Court of Arbitration for Sport.
English champions Manchester City have been banned from European competition for the next two seasons and fined $32.53 million by European football's governing body UEFA after an investigation into alleged breaches of Financial Fair Play (FFP) rules.
UEFA said in a statement that City had committed "serious breaches" of the rules while the Premier League club swiftly said they intended to appeal the decision to the Lausanne-based Court of Arbitration for Sport (CAS).
The ruling, if upheld, would mean City would not be able to compete in next season's Champions League should they again qualify for Europe's top club competition.
UEFA's FFP rules are intended to prevent clubs receiving unlimited amounts of money through inflated sponsorship deals with organisations related to the owners.
Announcing the ban a UEFA statement declared, "The Adjudicatory Chamber has imposed disciplinary measures on Manchester City Football Club directing that it shall be excluded from participation in UEFA club competitions in the next two seasons (ie the 2020/21 and 2021/22 seasons)."
European football's governing body said that City "failed to cooperate in the investigation."
"The adjudicatory chamber, having considered all the evidence, has found that Manchester City Football Club committed serious breaches of the UEFA Club Licensing and Financial Fair Play Regulations by overstating its sponsorship revenue in its accounts and in the break-even information submitted to UEFA between 2012 and 2016," European football's governing body said.
City lost a previous appeal to CAS over UEFA's original decision to refer them to its adjudicatory chamber over the alleged FFP violations.
The investigation into City was based on leaked emails published last year by German magazine Der Spiegel as part of "Football Leaks."
Guardiola's City outfit currently are second in the Premier League table, meaning that the fourth Champions League slot available for English teams would likely go to the fifth-placed club this term.
Sheffield United, promoted to the top flight last year, sit in fifth.
It is not the first time that Man City have fallen foul of FFP regulations, having been fined 60 million euros and seeing their Champions League squad reduced in May 2014.
Qatari-owned Paris Saint-Germain were also fined that year.
Seven-time European champions AC Milan were banned from this season's Europa League for FFP breaches.