West Ham have been linked with the 29-year-old but, while he accepts other clubs might be interested, Martinez does not want to comment on the situation.
The Spaniard said: "I am not surprised. When you are a defender who can come up with the type of goal he came up with on Saturday, you can get the type of compliments he gets behind closed doors outside.
"But I don't expect teams to talk about players who are under contract and I would never speak about players of other teams under contract at this stage of the season.
"I don't think this is the right time to do it."