The Belgium international has struggled to find his best form since his £28m transfer from Chelsea in the summer as he has notched just two goals this season.
However, Martinez is adamant that the 21-year-old is fully focused on getting back to his best at Goodison Park.
"Looking at that it could be a concern but looking at Rom, I can guarantee you there is no concern his mind set has changed," Martinez told reporters.
"Yes, he was trying to impress and find a permanent move, now his focus is winning games and winning trophies.
"He has become the most important player for Belgium. He has different goals and different targets, he's not in a position where he has got no challenge left, it is not that. Rom is very much focused and is ready to have a very strong season."
Everton face Aston Villa in their Premier League clash later today.