Karius has come under a lot of criticism for his role in shipping six goals in the last two of Liverpool's games.
Karius has come under fire from several pundits for his past two performance which has seen the Reds' summer signing ship six goals in the process.
Liverpool's Loris Karius during the match
But Mane has backed the 23-year-old, telling Sky Sports: "Everybody knows this is football and [criticism] can happen. We always train together and know his quality, what he can do to help the team.
"I think he will keep doing his best for the team, and do his best for the next game and keep helping, so what is behind is behind.
"I think in football everybody gets this kind of criticism. The reaction is more important now."
It looks likely that Jürgen Klopp will stick with Karius for the trip to Middlesbrough tomorrow evening, as the German will desperately seek a clean sheet as the Reds look to return to winning ways following their disappointing results against Bournemouth and West Ham United.
Liverpool's Sadio Mane in action with West Ham United's Manuel Lanzini
Mane indicates that his teammates are naturally supportive of him, while Klopp seems to have taken the headlines by hitting out at pundits - notably the Neville brothers - which seems to have taken a little bit of the spotlight off his goalkeeper, and moved it on to the manager.
Mane - who signed from Southampton in the summer - has had an impressive impact by scoring seven goals so far this season, and will look to add to that tally to help keep the side in contention over the festive period.