The Packers won 21-14 as the Bears were forced to play third-string quarterback Caleb Hanie after second-stringer Todd Collins was ineffective.
"Jay was hurt," Urlacher said. "I don't question his toughness. He's tough as hell. He's one of the toughest guys on our football team. He doesn't bitch. He doesn't complain when he gets hit. He goes out there and plays his ass off every Sunday. He practices every single day. So, no, we don't question his toughness."
Cutler tried to test the knee by riding a stationary bike on the sideline, where he remained throughout the game.
Shortly after the game, fans began calling sports talk shows to question Cutler's toughness. Urlacher was told that some players around the league were doing the same via Twitter.
"Nothing like jealous people who are sitting home watching," Urlacher said. "Players around the league you said, right? Yeah, love jealous people when they're watching our game on TV while their season is over."
In a posgame show on Fox, Urlacher again defended his quarterback when told fans were critical.
"Who cares what they think?" he said. "That's my response to them. They are not playing in this game. Jay was hurt, obviously. There's no reason for him to be out there if he can't get it done. He was obviously hurt pretty bad or he wouldn't have played.
"For them to question his toughness is stupid to me."
Bears center Olin Kreutz said he could see Cutler's leg shaking during a huddle in the second quarter.
Cutler is believed to have injured his knee on the final series of the first half.
Bears coach Lovie Smith said Cutler was disappointed.
"He was hurt, and he couldn't go," Smith said. "Trainers, doctors and all, they are the ones who really made that decision. As far as Jay he is like everyone else; he was disappointed he couldn't go out and play to help his team win."
Smith wasn't happy when asked again about Cutler not returning.
"He hurt his knee and he was out, all right? There's nothing else for me to tell you on that," Smith said. "I don't know exactly when it happened. He couldn't go, and we moved on. Let's go to some other questions, how about that?"
Cutler has been a lightning rod of controversy since coming over to the Bears in a trade with the Denver Broncos befoe the 2009 season. Cutler's first year with the Bears was disastrous as he threw 26 interceptions and Chicago finished 7-9.
But Cutler improved this season, despite an offensive line that yielded the most sacks in the NFL. And despite the constant battering he took, Cutler missed only one game after suffereing a concussion.
Cutler wasn't effective Sunday as he completed 6 of 13 passes for 80 yards and an interception in the first half. He tried to play in the third quarter, but after a three-and-out series, he left and would not return. He finished with a passer rating of 31.8.