The home side fielded a largely experimental side while City were without Robinho and new signing Emmanuel Adebayor. Debutant Zlatan Ibrahimovic had to wait until half time to make his bow and he had chances late on to salvage a draw for Barca.
While the Blaugrana dominated a tepid opening half it was Mark Hughes' men who struck just before the half hour with what was to be the only goal of the game.
Stephen Ireland lead a City counterattack and played a clever long ball forward to Petrov who finished coolly past the advancing Pinto from just inside the 18 yard box to put the Citizens in front.
Barca should have taken the lead themselves moments earlier when Bojan skied his effort over after Shay Given had saved from Jeffren.
Blaugrana coach Pep Guardiola made a host of changes at half-time including the introduction of Ibrahimovic who replaced Bojan. Substitutes Tiago, Messi and Ibra upped the tempo as the Catalan outfit went in search of an equaliser.
Given saved smartly with his feet from Ibrahimovic after 73 minutes and the Irish custodian was on hand again in the dying minutes to spoil the Swede's party after some neat foot work from Lionel Messi.
The former Inter striker combined with Tiago once more but failed to connect when he had the goal at his mercy from about seven yards and City cleared the ball to safety.
Despite a stoppage time effort from Messi hitting the upright, City held on and emerged victorious to claim the Joan Gamper Trophy, becoming only the third team in 20 years to beat Barcelona in the annual pre-season fixture.
Barcelona 0-1 Manchester City
0-1 Martin Petrov 28'
FC Barcelona:Pinto, Montoya (Alves 45), Fontas (Henry 63), Puyol (Bartra 31) (Pique 63), Maxwell (Muniesa, 63), Toure (Tiago 45) Busquets ( Keita 45), Gudjohnsen (Jonathan, 45), Pedro (Messi 45), Bojan (Ibrahimovic 45) and Jeffren (Gai Assulin, 54).
Manchester City:Given, Onuoha, Kolo Toure (Ben-Haim 45), Dunne, Zabaleta (Garrido 65), Weiss, Ireland, Barry (Etuhu 70), Wright-Phillips (Trippier 80) , Petrov, Tevez (Bellamy 65).
Paul Madden, Goal.com