Messi was helpless as the Albiceleste made little impact at the World Cup, going out in the last 16 to eventual champions France, who won 4-3.
After elimination, rumours swirled suggesting Messi's international retirement was inevitable and, although he has not actually called time on his Argentina career just yet, he did not make himself available for the current selection of interim coach Lionel Scaloni.
Nevertheless, Martinez is adamant Messi still has a vital role to play for the national team.
When asked by Clarin whether Messi is still needed, Martinez said: "Yes, without a doubt, because he is the best player in the world.
"He is Argentine and every time he wears the shirt of the national team we enjoy him to the fullest. He makes Argentine football keep growing.
"There were many things that I learned from him that were very useful and positive within the group, not only his relationship with the best [players], but also with the youngest.
"You learn a lot because here are the best and I try to make the most of all that to keep learning."
Martinez was handed his Argentina debut by Jorge Sampaoli in March, but the coach – who lost his job following the World Cup debacle – did not pick the young talent in the squad which went to Russia.
Yet, Martinez does not hold a grudge against Sampaoli for that disappointment.
"No, he did not cheat me," said Martinez, who missed the 3-0 friendly win over Guatemala due to a haematoma in his left calf.
"I always said that he was the coach and he was going to decide. I am convinced that the 23 [players] he chose for the World Cup were the best for him at that time.
"He asked me to make changes to my game, in what I had been doing, and I felt that from that side it hurt me because afterwards I was off the list.
"It was a very hard blow. I had a very big dream of being able to go to my first World Cup, to be there in the squad, but the responsibility is mine because I'm the one who enters the pitch.
"Now there is a technical staff [Scaloni and Juan Pablo Aimar] that comes to give a hand, who know what the national team is all about because they have played in it.
"This is important because they have transmitted what they experienced. There are also many young players who come doing things right in their clubs and now we, the players, have to take advantage of the opportunities they give us."