Newspaper photographs showed Townsend pushing Spurs fitness instructor Nathan Gardiner during a warm-down on the pitch after the 3-1 victory over Aston Villa on Monday.
Townsend had been left on the substitutes' bench throughout and has yet to start a Premier League game this season.
"When you behave in the wrong way, you need to pay," Pochettino told a news conference.
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"Because of Monday he is not available for selection.
"I can understand because I was a player and when you don't play you are not happy.
"But it's not normal behaviour, not the way to impress the manager.
"He has a future here. We believe in him and believe he can give us very good things."
Pochettino declined to say whether Townsend had been fined.
Spurs have lost only once in 11 league games and are fifth in the table but were beaten 2-1 away to Anderlecht in the Europa League two weeks ago.
(Reporting by Steve Tongue,; Editing by Neville Dalton)
