The pair were together at Fiorentina.
"As a person he's splendid and we've been friends for many years," Montolivo told Milan Channel.
"It will be wonderful if he arrives. Pazzini has done well in all the teams he played for. He is a fox in the box, very strong in the air and helps his sides to play well.
"It's wonderful to meet up here, at the club with the most trophies in the world, especially as I feel our squad is missing a player precisely like him."