The midfielder's dismissal sparked Juve's amazing collapse in Turin.
Del Neri said: "He certainly isn't happy about it. We gave him a few 'slaps', but trust he understood the mistake that he made. He must understand that when he loses his cool like that, it shows a lack of respect and damages the team by leaving us with 10 men.
"Having said that, we mustn't cancel out the improvements Melo had made before Thursday."
Juventus have reportedly handed a huge 150,000 fine to Melo.