Ronaldinho moved to the seven-times European champions from Barcelona in the summer and has scored seven goals since then in Serie A.
However, Milan have not won in four games in all competitions and Kaka has been less impressive in attack than usual this season.
"Ronnie has settled in very well and he's giving us a big hand, but before we were used to playing with automatic moves consolidated over the years," Kaka was quoted as saying by Saturday's La Gazzetta dello Sport.
"Me and Clarence [Seedorf] behind a forward, usually [Filippo] Inzaghi. With Ronaldinho the team has had to change set-up and we have to get used to having the same automatic moves with him.
"We play together in the national team, but it's not the same. It's a question of understanding, which is lacking a little."
Kaka said that he has had to "sacrifice himself" for the side on many occasions.
"I'm trying to adapt tactically because I often find myself playing closer to the midfielders," he explained.
"I'd like to play nearer the strikers, but I understand the needs of the team. The fact is that people expect something different from me, assists and goals, and if they don't arrive I get criticised."
Kaka is also looking forward to David Beckham's arrival on loan from LA Galaxy later this month.
"He'll help us achieve our goals for the season," he said. "Then maybe he'll fall in love with Milan and stay for many years instead of two months."