Laurent Blanc's men edged closer to the title with a 3-0 win over Reims on Saturday, Edinson Cavani finding the net before Aissa Mandi twice put through his own net.
Two wins from their remaining six games will guarantee the men from the capital a second straight league crown, though they can win the title at Lyon next weekend, should Monaco lose to Nantes on Sunday.
However, Pastore is refusing to take anything for granted.
"We still have two games to play in order to win the trophy and to be mathematically champions. It is not over yet," he said.
Saturday's victory came only three days before their UEFA Champions League quarter-final second leg at Chelsea.
PSG lead 3-1 from the first leg, however, Blanc's side will be without star striker Zlatan Ibrahimovic because of a hamstring injury.
But Pastore - scorer of the third goal in the first meeting - is confident PSG can finish the job without the Sweden international.
"One key player is missing within the squad, that's Ibra," the Argentinian added.
"But we also have Edinson who is going to play in his usual position in which, he's very dangerous in front of the goal.
"It's going to be fine, Ibra is missing but we have the most important players fit.
"All the squad felt very well with a lot of confidence. I hope we will perform as we know we can, getting the possession and to score a goal, it's very important.
"It's going to be a very difficult game, because playing Chelsea away is tough. The pitch is smaller. But we will try to focus only on us, playing well and win the game."
