Joel Lindpere put the Americans in front after 27 minutes with a neat finish after New York split the PSG defence.
The French side were also lucky not to concede a penalty when Carlos Mendes was tugged back by Loick Landre at a corner.
PSG - whose imminent £38million signing Javier Pastore is part of a summer spending spree since the Qatar Investment Authority bought a controlling stake in the club almost two months ago - stepped up a gear in the second half.
Christophe Jallet whipped a 20-yard free-kick just over the bar. However, despite dominating possession, the French side were unable to create more than a couple of half-chances.
New York face hosts Arsenal on Sunday, when former Gunner Thierry Henry will be hoping to take on his old club, while PSG will play Argentinian side Boca Juniors.