The title contenders were charged for returning to the pitch 60 seconds late after half-time in their 1-0 loss at Sporting Lisbon in the Europa League on March 8.
The figure is made all the more astonishing because Porto were only fined €20,000 (£16,700) when their fans racially abused Mario Balotelli and Yaya Toure in February.
Mancini told reporters: "I do not agree with this - I don't remember this. How many minutes did we lose? One?
"UEFA are like all the countries - all the countries need some money in this moment.
"Italy needs some money, England needs some money, Germany needs money. It is difficult for everyone and UEFA are the same probably!"
Despite his reservations for the organisations reasons behind the fine, the Italian coach has said the club will pay up
“We can do this,” Mancini added.
Manchester City won the reverse leg of the last-16 tie but were knocked out by the Portuguese club on away goals.