Postecoglou has left the door open for the Mali international to establish himself again as a key figure but has bridges to build.
“He has responsibilities, responsibility to the club, his team-mates, to our supporters and everyone associated with the club and he failed in those duties,” Postecoglou reflected.
“There have got to be sanctions for that. He won’t be available on Monday. We have suspended him for Monday’s game.
“Beyond that, there is also some trust-building that needs to happen between Biss and me, and Biss and the group.
“That’s what he needs to work hard at from now on to try and win that back and that has nothing to do with just one game. He may be suspended for one game but he is going to have to earn that.
“The door is open for him and hopefully we can help him to realise the decisions he makes impact more than just him and hopefully allow him to make better decisions going forward.”
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Asked what Bissouma must do next, Postecoglou was unequivocal, although this is not his first error of judgement after two red cards last season.
He added: “Behaviour, mate. It is quite simple. It is him making better choices moving forward and behaviour. He is obviously disappointed and was very apologetic, not just to me but to the club and everyone involved.
“That is just the first part of the process. The next part is behaviour now. Making sure, like I said, he does the things he needs to do.
“We all make mistakes and it is how you fight your way back from those mistakes and what you do is far more important than what you say.”
Tottenham remain active in the transfer window despite the arrival of forward Dominic Solanke last Saturday in a deal which could be worth £65 million.
Outgoings are a key priority with the club ready to sanction departures for Sergio Reguilon, Giovani Lo Celso and Manor Solomon.
Several young players could also exit on loan like Ash Phillips and Alfie Devine, with Jamie Donley close to a temporary switch to Leyton Orient.
However, 19-year-old forward Will Lankshear is currently set to remain part of Postecoglou’s first-team squad after an excellent pre-season.