Alpine team principal Otmar Szafnauer has claimed the outfit has a 14-driver shortlist to replace Alonso with reports suggesting that an exit clause in Gasly's AlphaTauri could allow the Frenchman to switch allegiances.
But speaking to SPORT1, Marko said: "There is no exit clause for Gasly. There was none before the summer break and there will be none after the summer break."
AlphaTauri team principal Franz Tost added: "It makes no sense for Red Bull to let Pierre go.
"If a Red Bull driver fails, there is no other adequate driver who can step in. Only Gasly can do that.”