Mane was dropped for poor timekeeping in defeat to Liverpool.
"Yes, of course. I punished the player because that's one of the rules and the instructions that we have with the players," Koeman said.
"Everyone is allowed to come one day late on a training session and that's no problem, but to play you have to be on time. That was on that day and after that day it's like before and that's no problem."
For the big stories and the banter follow us on Twitter: @tribalfootball