"Jadon is a great guy, but he needs to be a bit cleverer with certain things," Can told Sky after the two players linked up to score the winner in Dortmund's 1-0 win over Hertha Berlin.
"Obviously everyone needs to get their hair cut sometimes, but he needs to be a bit cleverer and a bit more grown up," added the former Liverpool and Juventus star.
Sancho and his Borussia Dortmund teammate Manuel Akanji were both fined by the German league on Friday for breaking stringent coronavrus guidelines to get haircuts at home.
Photos emerged of Sancho, 20, and 24-year-old Swiss defender Akanji having their hair styled in their respective homes, with neither the players nor the hairdresser wearing any personal protective equipment.
"We need to guide Jadon a bit. He can't afford to make mistakes like that in the future, and we can always talk to him about that as a team," said Can.
"It doesn't annoy us, but we know he has to be more disciplined with some things.
"I don't think he does it on purpose to cause a scandal. Maybe he just trusts people too much sometimes."