Martinez is not fazed by the efforts of his Everton predecessor, David Moyes, to lure Baines to Old Trafford.
He said: "A lot of people sometimes get upset when other clubs show an interest in your players.
"I always feel that it is a real compliment - it means Leighton is working and progressing really well.
"It's a very important year for him in terms of setting standards and trying to reach important things at the club.
"And, in a World Cup year, we are looking forward to seeing that real consistency of performances and making sure he can be himself."