Reports have linked McCarthy with the likes of Liverpool and Arsenal and Martinez claimed after the midfielder's two-goal performance in last weekend's 2-2 Barclays Premier League draw with QPR that the 22-year-old had "the potential to play anywhere in the world''.
The Spaniard added that "whenever he's ready we'll never stop him'' from leaving the club, but Martinez on Thursday stressed McCarthy is still developing and says the distraction of transfer talk is the last thing the Republic of Ireland international needs.
He then nodded when questioned whether or not he thought McCarthy would remain a Wigan player for the remainder of the campaign.
Asked if there had been any firm interest in McCarthy, Martinez said: "No."
Speaking this morning ahead of Saturday's league match at Norwich, Martinez added: "We will always feel really pleased with compliments towards our players.
"But James McCarthy is a young man - at 22 he is still developing.
"One day he will be challenging to win titles and to be in the highest position in the game, there is no two ways about it.
"But he is still developing and the performance that he had on Saturday shows that he is developing in the right way.
"He knows that and he knows as well that it is an important time for his role with the national team.
"The last thing he needs now is to be distracted from his good work and the way he is developing.''
Martinez is adamant the January transfer window will only prove beneficial for the Wigan squad.
"In January, we are not going to do anything else apart from adding players that can help us in becoming a bit stronger in the way we want to play," said Martinez, whose side are currently 18th but just two points behind 14th-placed Newcastle.
"The January window is going to be positive for us, I have no doubts about that."
Wigan will soon have a new face around the club, with the manager on Thursday confirming Dutch midfielder Ferrie Bodde is to train with them.
Bodde, signed by Martinez for Swansea in 2007, has been without a team since he was released by the Welsh outfit over the summer.
The 30-year-old has been blighted by knee problems and last played first-team football in the 2009/10 season.
He has been training with his first club ADO Den Haag back in his homeland and will now be reunited at Wigan with Martinez, who is giving little away for the time being about the prospect of the player signing a deal at the DW Stadium.
"It is just having him training, for him to see how he feels and how the knee reacts,'' Martinez said.
"It is just to see how he gets back into shape, nothing else.
"I always said he was the best player in his generation and it has been a real shame that out of the players that started something special at Swansea, he is the only one who has not played in the Premier League.
"I hope that one day he can get that reward. But that is a long way off.
"It is important that he gets himself fully fit and sees how he feels. We are going to try to help him in that respect and see if he is fully recovered.''
Martinez also reported no further developments in Wigan's pursuit of Roger Espinoza, the versatile 26-year-old Honduras international whose work permit hearing ahead of his proposed move to the Latics from Sporting Kansas City takes place in the next few weeks.
Meanwhile, Martinez has hinted that both skipper Gary Caldwell - who it had been thought would definitely miss the Norwich game - and Ivan Ramis could have a chance of featuring on Saturday.
The two centre-backs have each been nursing hamstring injuries.
If fit, Caldwell is available for selection having completed a one-match suspension, as has fellow defender Maynor Figueroa.