The 32-year-old Colombian will be out of contract at the end of the season, leading to suggestions that he could be sold in January.
However, Heidel told spox.com: "Elkin Soto has our perfect appreciation. He became a full part of this club a very long time ago. We are definitely out to sign a new contract with Elkin Soto to ensure he stays on at our club."
Soto has made 16 appearances for his country.