Keeping Haaland tight will not be enough to silence the Man City attack. Because Man City's forward players actually have almost even skills, that is, they can always endanger the opponent's defense. Even if Inter Milan focuses too much on Haaland, Inter Milan's fate could be the same as what happened to Real Madrid in the semi-finals.
If the Inter Milan defense keeps their focus mainly on Haaland, then I think they would be making a big mistake. They might focus mainly on Haaland and forget other players are equally as dangerous. Manchester City has capable midfielders that could also score goals. Haaland is instrumental in scoring goals as he finishes beautifully but i believe Manchester City could always do without him.
Gundogan and De Bruyne, as well as Grealish are players in my opinion to also watch out for that could cause some problems for Inter Milan.