Messi, 33, is out of contract in June and can discuss terms on a pre-contract agreement with foreign clubs from January 1.
"You will have to ask Leo, I don't know," Pique replied at a question and answer session for the CRIS Cancer Foundation when asked if Messi would remain at the Catalan club beyond the summer.
"We hope he stays. It's a personal decision. We will see.
"But for as long as he's wearing the Barca shirt, there is always hope. We hope to seduce him to stay for many more years."