City host the Spanish champions at the Etihad Stadium on Tuesday a fortnight after being thrashed 4-0 by the same opponents in the Nou Camp.
That has left City facing a battle to qualify for the Champions League last 16 from Group C having also been held to a draw by Celtic.
City manager Guardiola, speaking at his pre-match press conference, said: "I think we know what we have to do to beat them and hopefully our quality up front will make a difference.
"We have to play in that way - like a final
It's not a final for them, it is a final for us
There are just three games left and we dropped two points in Glasgow, so we have to recover those points in the next two games.
"We have to be focused for 90 minutes, knowing they are going to provoke mistakes because of the quality they have.
"But we had a few chances and have to keep going in that sense and try to finish better than we did in Barcelona.
"We will try
I have never entered a match thinking we can't win but we have to play almost perfectly."
Premier League leaders City go into the game having ended a six-match winless sequence with an emphatic 4-0 defeat of West Brom at the weekend.
Former Barcelona boss Guardiola said: "Winning the last game will help us a lot
When you play a game having won the previous one the feeling is much better
We play the best tomorrow and we're going to try to win."
Source : PA
Source: PA