Pastore joined the French side in a big-money move from Palermo in 2011.
The 24-year-old has struggled to impress in Paris and his agent has recently admitted the midfielder has grown unhappy with life in France.
"In football there are always ups and downs," said Marcelo Simonian.
"He has been happy there, but now is not the time for nostalgia. We will see what happens in the next few months."
Liverpool are reportedly ready to make a big money marquee signing in January and around £17million would be enough to sign Pastore from PSG.
Napoli and AC Milan are also reportedly interested in the highly-rated midfielder.