Nasri felt the Premier League winners paid too much respect to the four-time European champions when they met in the last 16 of the elite competition a year ago.
Barca won 4-1 on aggregate but City have a chance for revenge having been paired with the Catalan giants at the same stage for a second successive season.
Having come through a tough group phase in dramatic circumstances, Nasri now believes City are a much tougher proposition than they were 12 months ago.
The Frenchman, speaking at City's pre-match press conference, said: "I think we respected them too much but, at the same time, last year didn't have enough experience to compete with a club like this, with its history
They know how to deal with this kind of game
They know how to win the Champions League.
"For us it was the first time that we went through the group stage
I think it was just too much of a big game for us
We were not ready.
"But I think this year is totally different
We know what we are capable of
We are going to respect them as players but we are not going to be scared
We are just going to play and try to win it."
Like last year, City host the first leg, with star-studded Barca at the Etihad Stadium on Tuesday.
Manager Manuel Pellegrini adopted an uncharacteristically defensive approach last time and the move backfired with the Spanish side running out 2-0 winners after the sending off of Martin Demichelis.
They completed the job with a 2-1 win at the Nou Camp in a clash that saw City have another man dismissed in Pablo Zabaleta, but P ellegrini believes his team are in a better position to beat Barcelona than they were a year ago
The Chilean courted controversy himself after the first leg 12 months ago when he raged at referee Jonas Eriksson over perceived injustices.
Pellegrini said: "I think that last year was different to this year.
"We arrived at this stage of the Champions League after playing 19 games in two months, and I don't think it was our best moment.
"But I hope this year we will do it after not playing so many games
I think that our team is in a good moment, although we also recognise we are going to be playing against a very strong team."
City must again make do without talisman Yaya Toure as he completes his three-match ban for his dismissal against CSKA Moscow in November.
Fellow midfielder James Milner is available after overcoming the knee injury that kept him out of Saturday's 5-0 win over Newcastle.
The Catalans come into the game under a cloud after Lionel Messi and Gerard Pique were both pictured outside a casino in Barcelona late on Sunday night, hours before they were to travel to Manchester
Coming soon after the team's 11-game winning streak was ended by defeat to Malaga in the Primera Division on Saturday, the photographs have prompted renewed talk of crisis at the Nou Camp following difficulties earlier in the season.
But coach Luis Enrique and Pique himself were bemused by discussion of the matter as they arrived at the Etihad Stadium for a press conference, and t here was certainly no suggestion that either player had broken a curfew or any club rules
"This guy must work for one of the Spanish channels!" said Luis Enique when the question was put to him by an English journalist
"I concentrate on football, not stuff outside it
No gossip
I am not interested."
Pique, the former Manchester United defender, did not deny that he had been to the casino and was not particularly flustered by mention of it.
The 28-year-old said: "It is my private life
We just had a nice time there."
Focusing on the game, Luis Enrique is expecting a close contest against City.
"We are hoping to win the trophy so we have to go through games like this," he said
"I don't think there is a favourite in this game
"I don't know if there is a bigger gap or if the gap has closed
City have strengthened in the summer, we have too.
"What happens on the pitch tomorrow will show if the gap has closed."
Source : PA
Source: PA