The Brazil international is full of praise for the 20-year-old Argentina playmaker and has no doubts they would form a mouthwatering pairing.
"If (Milan vice-president) Adriano Galliani ever gave me the reins to the transfer market, I would sign Messi," said Kaka.
"At this moment in time he is a player I like to watch. He can make the difference in an incredible way. If I could sign any player, yes, it would be Messi.
"Can we play together? Of course. I can play with Messi, with Ronaldinho, with Alexandre Pato and with Pippo Inzaghi. It is just an issue of adapting to each other."
The 26-year-old also revealed he has tried to contact his team-mate and compatriot Ronaldo, who has recently been caught up in a scandal involving three transsexual prostitutes in Brazil.
"I tried calling him but we know Ronnie is a bit out of the loop at the moment," said Kaka. "I respect him for what he has been through and this is a difficult time.
"I try to stay close to him as much as possible in every situation. I respect him a great deal and he is a very good person. Those who know him are aware of his values.
"Everybody can make a mistake. I do not judge him for what he did and that error, which he has taken full responsibility for."