City face Cisse tomorrow on the back of his two-goal performance at Chelsea on Wednesday night.
"Any player can improve a lot in every year," said Mancini.
"Maybe Cisse has found a good squad, that plays football very well. It is another situation for him and another type of football. Maybe that is better.
"It is always difficult for someone who arrived in January.
"But he has scored 13 goals. However, even at Freiburg he played very well, even if he didn't score quite so many."