City have been handed a testing tie against the Catalan giants in the last 16 of the Champions League.
Pellegrini's men might have avoided such a big clash had they not misunderstood the group stage goal difference rules last week.
City beat Bayern Munich 3-2 but Pellegrini failed to realise that victory by one more goal would have secured top spot in their group and a theoretically more favourable draw.
Yet simply after beating the European champions, and then scoring six past Barclays Premier League leaders Arsenal, Pellegrini is confident enough after the draw.
He said: "I think they will be very concerned also. Barcelona is not the team it was two years ago.
"I think it is a beautiful game with two very good teams."
While Pellegrini accepts he miscalculated in Munich, he insists his side would have faced a tough draw from whichever position they had finished in the group.
He said: "All the 16 teams that play in the last 16 are the best teams of Europe - so Real Madrid, Barcelona, Atletico Madrid, Borussia Dortmund, Paris Saint-Germain for me was exactly the same."
Despite what happened in Munich - and Pellegrini's failure to send on top scorer Sergio Aguero continues to be picked out by critics - the Chilean insists his team did not stop trying to score a fourth.
He feels too much is being made of the matter and the team are not receiving enough credit for their achievement in recovering from 2-0 down.
He said: "There was no confusion. Maybe a mistake could be if I thought 3-2 was enough and we didn't try to score the fourth goal - but we tried to score the fourth and fifth goal but we couldn't do it.
"I respect the critics but I think they are absolutely confused against who we were playing."
Pellegrini believes City, who have qualified for the knockout phase for the first time, will take a lot from claiming such a notable scalp.
He said: "A lot of confidence. The most important thing, and we had already done it, was to qualify for the next round but to play against Bayern was a big test for what we can do in the future."
The tie will bring Barca star Lionel Messi up against his Argentina team-mate Aguero.
Pellegrini recently said he rates Aguero third, behind Messi and Cristiano Ronaldo, among the world's best players.
But the Chilean said: "It is not only Messi and Aguero. The two teams have top players and we will see which play better in that round of Champions League.
"But that is in February. We will worry about that later."
While that prospect is an enticing one, City will have to make do without Aguero for the immediate future.
Pellegrini has confirmed he expects the prolific forward, who has scored 19 goals this season, to be out for at least a month with a calf injury.
City are still to learn the full extent of the problem but Aguero is set to miss the Boxing Day clash with Liverpool as well as other Barclays Premier League games against Fulham, Crystal Palace and Swansea.
Aguero was injured early in the second half of Saturday's impressive 6-3 defeat of Arsenal.
Pellegrini said: "I think he will be at least one month out.
"He has a calf injury. Maybe the doctor can say exactly how many weeks he will be."
Pellegrini was speaking at a press conference to preview his side's midweek Capital One Cup quart-final at Leicester, for which changes were likely anyway.
He said: "Of course, when you have a good squad, it is easy for the manager to make changes. I trust in this squad.
"That's why we went last week to play against Bayern with five or six players that don't normally start and we won.
"After Bayern we made six or seven changes against Arsenal and won. We will make some changes in the same way.
"I think it is an important cup. That is why we try from the beginning to play from the beginning with a good team.
"We hope we can continue with this cup and always a final in Wembley is important."