Gattuso left the Rossonero last week.
“All we can do is wait and for the good of Milan, I hope that the decisions being made are the right ones," Reina told Sky Sport Italia.
“We must always put the effort in. The coach said the squad is in good hands, I have no doubts that the club will continue to grow.
“Gattuso's decision to leave is to be respected. He deserves credit, because he proved himself once again a man of genuine values."