The Germany attacker has just fired Bayer to a first ever Bundesliga title and is attracting interest from the likes of Real Madrid, Barcelona and Liverpool.
Carro told Radio Marca: "No one is unsellable, but for less than 150 million (euros) it is not relevant for Wirtz to leave."
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Wirtz, 20, has a deal with Bayer until 2027.
The attacking midfielder has accounted for eleven goals and ten assists in 29 appearances in the Bundesliga this season.