The 25-year-old fell foul of the club's hierarchy when missing a training session before their game against Sale on March 3.
Saints were beaten by the Sharks and, after the contest, coach Alan Gaffney suggested that the giant Wales wide man did not want to play in the match.
He was free to play for Saints on weekends when there was not a Six Nations game as the Welsh Rugby Union do not have an agreement with English Premiership clubs about withdrawing players.
Northampton's chief executive Mark Darbon says North, who is available for the final five fixtures of the season but will return to Welsh club rugby in the summer, has taken his punishment and everyone should now move on.
"George accepts the disciplinary action we have taken," he said.
"George has enormous affection for this club and its supporters, and is fully committed to helping the club finish the Premiership season as strongly as possible.
"We now consider this matter resolved and won't be commenting further."