The European governing body this week hit City with a £24,740 punishment for delaying the start of the second half of last month's Europa League game at Sporting Lisbon by up to one minute.
The decision prompted criticism in many quarters as Porto were fined a mere £16,700 for their fans' racial abuse of City players Mario Balotelli and Yaya Toure in February.
Mancini joked that UEFA must be struggling financially in economically difficult times.
The Italian said: "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!"
Mancini added that City would pay the fine.
"We can do this," he said.
City were beaten 1-0 in Lisbon on March 8 and went on to lose the last-16 tie on away goals after a 3-2 win at the Etihad Stadium the following week.
Porto received their punishment last week after a complaint by City following their last-32 first leg at the Estadio do Dragao on February 16.
Balotelli and Toure were both subjected to monkey taunts during the game, which City won 2-1.