The Parisian outfit have considerably strengthened their side since being taken over by Qatar Investment Authority in 2011, with Pastore one of their first signings 12 months ago.
The former Palermo man was eager for his side to buy Lavezzi, having played with him for the Argentina national team; and he has been impressed by the forward's impact in his short time at the club.
"It has been obvious in his first days at PSG: Lavezzi is an extraordinary person. He has a good character so is well integrated into the group, and he is an important player that can make a difference here. I am glad of his arrival in Paris," El Flaco told Sky Sports.
"We played a friendly match against CSKA Moscow and after only four days with us, El Pocho has made a difference in attack, as always."
PSG finished second in last season's Ligue 1 table, three points behind surprise winners Montpellier.