Lukaku caused a stir this week when quotes attributed to the former Chelsea man suggested he would like a move back to "a top club" in the future.
The Belgium international then put in an inspired display at Young Boys in the UEFA Europa League on Thursday, netting a hat-trick in a 4-1 win that sees Everton as overwhelming favourites to progress to the last 16 of the competition.
"Footballers should be measured by what they do on the pitch," Martinez said in a press conference on Friday.
"He was the perfect Everton ambassador and I was delighted to see that performance.
"You can take things out of context. There's no issue whatsoever. I understand how it works, trying to get a headline, and that's where a player shouldn't be judged.
"As a striker you need to be fed with goals otherwise you don't feel well. Romelu was unstoppable at times, not just scoring a hat-trick, but creating the chances and was always in the right place.
"He could have scored six, and he probably scored the hardest chances, but what pleases me is the responsibility that he took.
"He lead the line fantastically well and our combination play was based around him. Our attacking play was strong and it's important now that Rom keeps on that level."
