Kylian Mbappe must sign a new contract if he wants to stay at Paris St-Germain, club president Nasser Al-Khelaifi says.
Al-Khelaifi was speaking at a news conference to introduce Luis Enrique as PSG's new manager following the sacking of Christophe Galtier.
France striker Mbappe, 24, has told PSG that he will not extend his contract with them beyond 2024.
"Our position is very clear," said Al-Khelaifi.
"If Kylian Mbappe wants to stay - we want him to stay - he needs to sign a new contract.
"We cannot let the best player in the world right now leave for free. That is impossible."
Mbappe has the option of a further year when his deal expires after next season but has said that while he plans to stay with the French champions for the 2023-24 campaign, he does not intend to activate the contract extension.
If that is the case, he would be able to leave for free next summer.
"This is a French club and, as he has said, he is not planning to leave for free," added Al-Khelaifi.
"If somebody has changed his mind, it is not our fault."
Mbappe, who joined PSG in 2017 initially on loan from Monaco before a 180m euros (£165.7m) transfer, has scored 212 goals in 260 games for the club.
He finished as Ligue 1's top scorer in each of the past five seasons and has won five league titles in his six seasons at PSG.
