The Norway defender says Bendtner was never going to make it at Arsenal because of his attitude and poor work ethic.
Nordtveit, 21, who joined Borussia Monchengladbach last December, told Danish channel TV2 sport: "You could not say much to him (about his game) because it doesn't take much for him not to like you.
"He has his own way of doing things, but he could have made more of an effort in training when he was at Arsenal.
"It was disappointing for Bendtner to have so little time on the field in the last half year. But Arsene Wenger always wants to play with his best players and that's what he did."
Bendtner joined Sunderland on-loan last week.