The English winger has been banned from all first team activity involving United due to a bust up with manager Erik ten Hag.
After the Dutch head coach stated Sancho was not training to a high standard, the winger went onto social media to criticize his manager.
Speaking to talkSPORT, O'Shea said:"Very simply for me, it boils down to an argument between the manager and a player. Ultimately, the manager generally wins and that's always been the case.
"If Jadon wants to get back playing football for United as quickly as possible, look maybe he might not mean it but just go and apologize.
"Then you're back involved in the squad and back involved with a chance to play. I know it's not ideal with how public it's been but it can be resolved very quickly."