Icardi will not be involved at San Siro when the city rivals clash, as a stand-off over his Inter future and conflicting takes from club and player over his fitness continue.
Milan enters the game in contrastingly high spirits, a point and a place ahead of Inter in third after a run of five consecutive wins in Serie A.
Asked about Icardi, who scored a last-gasp winner when the sides met earlier this season but has now been stripped of the Inter captaincy, Gattuso said: "The way I see it, even the best player in the world should respect his team-mates.
"Respect for players and those who represent them is fundamental. The locker room is sacred.
"I appreciate when my players speak their mind in person."
Milan's recent upturn owes much to the prolific form of Krzysztof Piatek, who has scored six goals in as many league starts since joining from Genoa in January.
The Poland striker's dedication in training was initially mistaken for dissatisfaction by Gattuso, who is delighted by his recent recruit's attitude.
"We do not speak much, he prefers actions on the pitch," he said.
"I am beginning to see him smile more often. At the beginning I thought he was upset with me.
"He is dedicated and likes to train, he knows what needs to be done."
Gattuso added: "The team has to make the difference on the pitch. Few players are capable of winning a game on their own, we are not in a condition to win based on just one player."