The 27-year-old striker, who scored 24 goals last season, has been linked with moves to both Tottenham Hotspur and Juventus.
"Llorente will not be going anywhere in the winter transfer market and we will not be signing anyone," said Bilbao president Jose Urrutia.
"We took a decision at the start of the season on economic, sporting and philosophical grounds. Athletic are stronger and more competitive with Fernando in the ranks."
Despite his goal-scoring exploits during the last campaign, Llorente has found the net just once this term.