The combative Spaniard is known for his tough-tackling, and has picked up 11 yellow cards and been sent of twice in 25 appearances for Bilbao this season.
Old Trafford has been touted as a potential destination for Martinez, as Sir Alex Ferguson scours the market for possible midfield reinforcements.
However, Manchester City may now well be frontrunners to sign the 23-year-old, after a reported recommendation from midfield maestro David Silva.
According to The Sun, Silva has urged Roberto Mancini to bring Martinez to the Etihad Stadium, although will have to pay around £25 million to complete a deal.
Bilbao, though, maintain they have no intention of letting Martinez leave San Mamés and will do everything they can to keep him at the club.
"We don't want Javi to go — only an incredible offer could change our minds," a Bilbao source reportedly told The Sun.
Martinez has made seven senior appearances for Spain, and was a member of last summer's triumphant under-21 squad at the European Championships.