Marseille president Jacques-Henri Eyraud claims he would ignore an €80 million ($94m) offer for Florian Thauvin.
Thauvin's form, which also earned him a place in France's World Cup squad, underlines the improvements he has made since struggling desperately at Newcastle United after leaving Marseille for England in 2015.
And Eyraud has no desire to see the winger depart the Europa League finalists for a second time.
"If there is an offer of 80 million euros for Florian Thauvin, I won't even look at it!" he told SFR Sport.
"He's aware that OM have given him a lot of support. This is not the end of the story. There are still even more beautiful pages to write. We're counting on him for next season to take us even further.
"He has had an extraordinary season. He's a great player. He has grown, he has matured, and the coach has helped him a lot to achieve his goals, even to surpass them.
"The numbers speak for him and it's a great satisfaction to see him in [Didier] Deschamps' squad."
Eyraud is also eager to keep head coach Rudi Garcia at Stade Velodrome beyond this season.
The former Roma boss was appointed just three days after Marseille was bought by American Franck McCourt and Eyraud considers it among the best things he has done for the club.
"He's one of my best decisions. I'm so happy to have taken it," he said.
"He has character, a clear mental strength, he can handle a dressing room. He's close to the players and shows all the necessary authority.
"He's had a great season and he'll continue with us."
Marseille finished fourth in Ligue 1 and reached the Europa League final, where they lost 3-0 to Atletico Madrid.