"It was a strange day for every football supporter, a surprise. We heard about the Super League the past few months but I was sure it was not going to happen," Ancelotti told reporters ahead of Friday's Premier League trip to Arsenal.
"The 12 clubs were wrong. They didn't take into consideration the opinion of the players and managers and the supporters.
"Because playing 60 minutes against Belarus and scoring one of eight goals is not quite the same as if he comes on against Everton and helps them to a 3-0 win by scoring a couple,"
England striker Calvert-Lewin, who has scored 20 goals in 30 games for club and country this season, came off with a tight hamstring in Wednesday's epic 5-4 FA Cup victory over Tottenham Hotspur.
"We have back Andre Gomes, James, Josh King, and in the next week we think Allan will be back, so the squad is ready for the next games," Ancelotti said.