The Republic of Ireland defender has enjoyed an eye-catching season, with seven goals from right-back, and has a contract at Goodison Park which runs until June 2018.
However, United manager David Moyes is reportedly interested in bringing the 25-year-old to Old Trafford in the summer but Spaniard Martinez was adamant no-one had been in touch to discuss the player's future.
He said: "It must be a different Seamus Coleman because we've never had any discussions with anyone.
"I think the truth is that Seamus has been having a very good season and we want that to continue and hopefully in the next 10 games he can continue with the levels he's shown and developing.
"He's becoming a very, very important player at Everton, a very important player for his national team and obviously we want Seamus here for a long, long time. So it's nothing to comment on.
"We've got a clear strategy of how we want to keep this group together, we've got a new generation coming through (and) we're going to keep the senior players for as long as we can.
"Obviously that's something we work on and it's not going to change because of media speculation."
Martinez went on to say the whole club were boosted by a new shirt sponsorship agreement with Thai beer company Chang, which is worth more than £16million over the next three years.
The deal puts Everton around eighth in terms of the annual income it generates, just behind Newcastle and on a par with Aston Villa, Fulham and Sunderland.
However, Martinez said the club's league finish - and whether they can secure European qualification - will have more of a bearing on his transfer plans.
"Obviously the sponsorship deal with Chang is a relationship which has been over 10 years and you don't get these relationships in Premier League clubs and we value that," he said.
"To be able to sign a new three-year deal is exciting for both parties but it doesn't change anything (on transfers).
"We are in that key moment of the campaign with 30 points to play for and every player is desperate to have a big say and that is the only thing that matters.
"Whatever happens in the summer will be the next step but many of the decisions will depend on how we do in the next 10 games so you can imagine the focus goes into those games."
Martinez's men are sixth in the league, one place outside the automatic Europa League qualification position, but have two games in hand to make up the two points to fifth-placed Tottenham who have 53 points from 30 games.
And with Capital One Cup winners Manchester City set to qualify for the UEFA Champions League, there is very chance that sixth could be enough to secure a Europa League berth next season.