Point guard Deron Williams described the team's playoff loss to the Chicago Bulls earlier this year as "soft".
King told the team's website: "You saw it. There were certain games where things just happened that you can't allow to happen. At some point, you've got to knock a guy on his [butt] if they're doing things. You've got to take a hard foul and let them know you just can't do that. And we didn't do it.
"In certain games of the playoffs, in certain games of the regular season, it's just basketball, but if a guy has got a layup, you've got to put him on his [butt] so they don't do it."
The Nets face the Washington Wizards in pre-season on Tuesday.