Galliani admits the pair went to PSG with the need to "balance the books".
“We must explain why we sold Ibrahimovic and Thiago Silva,” Galliani told L’Equipe.
“Milan took the decision, amid total agreement between the club and management staff, to balance the books.
“This saw us forced to give up on some very big salaries. It would’ve been impossible to sustain the costs of the wage bill without cutting those contracts that had become too damaging for us.
“From then on, we made the painful decision to sell the two or three players with the highest wages. It was a decision by the club that I shared.
“We reduced losses significantly, going from €80m last season to a maximum of €5m for this financial year.
“Last year our wage bill was €150m, this year it is around €100m. These are figures I am revealing for the first time.
“Balancing the books means we will not have to make any more sacrifices next summer, where we will not be selling our top players.
“The wage bill has dropped by around 40 per cent, meaning we are now a healthy club. If Milan could’ve continued paying €12m to Ibra and €6m to Thiago Silva, then we wouldn’t have sold them.
“Without these cuts, we would never have fitted within the parameters of UEFA’s Financial Fair Play rules.”