The 28-year-old playmaker has managed just four starts in Ligue 1 this season and finds himself struggling for game time in a squad that also contains Julian Draxler, Lucas Moura, Kylian Mbappe, Neymar and Edinson Cavani.
Pastore claimed earlier this month he will not seek a move away from Parc des Princes to boost his hopes of being selected by Argentina for the World Cup in Russia next year.
But the former Palermo man, who was introduced in the 82nd minute of a 2-1 win over the reigning champions at Stade Louis II, now appears to be weighing up the prospect of a transfer away from the French capital.
"I was disappointed," he was quoted as saying by L'Equipe.
"I always want to play, I do not play important matches like in the Champions League or today against Monaco. It was more or less like that all year long.
"I have already said it, I'm going to think about my future but the important thing is to try to help the team during the ten minutes that I enter the field."
With his future being called into question, Pastore was recently talked up as a possible transfer target for Manchester United by Red Devils legend Eric Cantona.
Quizzed by the Full Time DEVILS on who the club's next No. 7 could be, the Frenchman said: "I love Pastore.
"He plays for Paris but he doesn't play in the team. They have two great players - Pastore and [Hatem] Ben Arfa and neither of them play.”