The Manchester United boss has seen striker Marcus Rashford come under scrutiny this week as he missed last weekend's FA Cup game against Newport after partying in Belfast and he warned that those playing at the top level must be responsible for their behaviour away from the field.
Ten Hag said: "It's nothing to do with me but in football, you need discipline and that is on the pitch but also off the pitch.
"There is a line between, every player, every professional knows this, what is required."
It is the third time since Ten Hag became United coach that the England international has been in hot water for his off-field antics but the coach remained tight-lipped when asked if Rashford has been showing disrespect with persistent transgressions.
The United manager said: "It's nothing to do with that but as I said, let's focus on the game, let's move on. We have to focus on winning football games.
"He has taken responsibility and for the rest it's an internal matter. Case closed."
Rashford is set to feature for United in the Premier League fixture against Wolves on Thursday (01.02.24) and Ten Hag hopes that the striker can continue to forge a partnership with team-mate Rasmus Hojlund.
He said: "There's a strong bond developing between Marcus and Rasmus Hojlund and we want to continue that process."