The Sicilian club's president, Maurizio Zamparini, has confirmed that negotiations are at an advanced stage and believes a deal is imminent.
"I'll only talk after the sale. We're close to finalising it. It's only a matter of time," Zamparini told Sky Italia.
The offers Palermo have accepted for 22-year-old Pastore are said to be around €40m (£35m).
PSG have been active in the transfer market since the Qatar Investment Authority bought a 70% stake in the Parisian club in May.
They have already spent €38m (£33.5m) this summer, including a €10m (£9m) move for Frenchman Jeremy Menez from Roma.