Baines was the subject of a rejected bid from Manchester United during the close season.
With the January transfer window approaching, the 29-year-old’s future is set to come under scrutiny again.
However, Martinez insists Everton do not need to sell.
The Spaniard told the Sunday Mirror: "If I want a player I need to match the valuation to then put the other club and the player in a situation to make a decision.
"We have never been in a situation where the valuation has been matched with Leighton.
"We don't want to sell Leighton. When you are in a position when you have to bring money then you are relying on what you can sell. We are not in that position.
"As a club we don't need the money. We don't need to balance the books and that is a situation we wanted to have - to make football decisions, not financial decisions.
"We're not in talks with him about a deal. We don't have to say it publicly but nobody is for sale."
Martinez, who succeeded current United boss David Moyes at Goodison Park, has been hailed by midfielder Steven Pienaar for placing trust in Everton's players.
Everton sit fifth in the Premier League having lost just once this season, and Pienaar is delighted to see Martinez’s style of play reaping rewards.
"This season we've been more patient. His (Martinez's) philosophy is if you keep the ball, you're not going to work as hard as the other team," said the South African.
"The trust the manager has in his players is unbelievable. He wants us to go out there and dominate a game. It takes a lot of courage and hard work. To keep the ball is not only passing – you have to move, you have to be fit.
"He came in and told us, 'Listen, you have to get over your fears now – just go out and enjoy the game'.
"He is so positive and it carries over to the team and makes us more relaxed."
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