Townsend was pictured pushing and arguing with Spurs trainer Nathan Gardiner on the pitch at White Hart Lane following the team’s 3-1 win over Aston Villa.
The 24-year-old is yet to start a Barclays Premier League match this season and was an unused substitute against Villa, with Pochettino preferring to bring on Ryan Mason and 18-year-old Josh Onomah in the second half.
Townsend has since been banned from first team training and will not be part of the squad for Thursday night’s Europa League match at home to Anderlecht.
“He did not train with the group. He is not available to be selected tomorrow, he is not in the squad,” Pochettino said.
“It’s because of Monday. When you behave in the wrong way you always need to pay.
“It’s always my decision when he is available again to be part of the squad.
“Discipline for me is very important. I can understand the player – we have a young squad and a player can make a mistake – but when you cross the limit it is important to stop that.
“As a manager I am very fair but the discipline is very important. The staff need to show respect to the player and the player needs to show respect to the staff.”
Townsend has apologised for the spat but is believed to be considering his future at Tottenham, where the likes of Christian Eriksen, Mousa Dembele, Erik Lamela and Nacer Chadli have all moved ahead of him in the pecking order.
A number of clubs reportedly showed an interest last summer and Townsend is likely to want more regular football to be in contention for England’s Euro 2016 squad next year.
“Has he apologised? Yes, he recognised it was a mistake,” Pochettino said.
“I can understand because I was a player and when you don’t play you’re unhappy and sometimes your expectation is bigger than the manager provides you.
“But it was not normal behaviour. He is young and you need to understand that it isn’t the way to impress the manager.
“He needs to learn about football, about behaviour, about discipline, about a lot of things.
“Football is not only about taking the ball in your feet and playing. You have a responsibility as a professional.”
Pochettino suggested the club have fined Townsend for the incident but insists the player can still have a future at White Hart Lane.
“All players have a future. It’s up to them to have a future here. Football can change quick,” Pochettino said.
“He is in the squad because we believe in him and believe he can give us very good things, but it is up to the player when he has the chance to impress me and show I am wrong in my decision.
“Has he been fined? It’s a private matter. I think it’s obvious. Your question and my answer.”
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