Barkley has been a revelation this season for Everton, nailing down a regular place in Martinez's starting XI and breaking into the England squad.
The 20-year-old is being tipped to be part of the England squad for next summer's World Cup finals after making an impression on Roy Hodgson.
Barkley's form has seen his name being linked with the likes of Chelsea, Manchester City and Manchester United, with the playmaker catching the eye in several big games this term.
Martinez is trying to keep Barkley's feet on the ground and has called on him to concentrate on Everton, and not think too much about playing in Brazil with England.
"In football a week is an eternity so for a few months it is going to be a waste of time thinking about what can happen in the future," said Martinez.
"In football you need to concentrate on the day-to-day work and that's where Ross is.
"But all he needs to do now is concentrate on his club role and make sure he is ready to help the team and enjoy his season and develop, and grow.
"Sometimes you get confused as a player how you are going to affect what happens in the national team - but it is very easy. It is about what you do at club level."