Sunday's World Cup final against Spain ended in a 1-0 defeat for Argentina as they failed to defend their title as Ferran Torres scored in extra time.
Martinez started seven of his country's eight matches in the 2026 tournament before picking up an injury in the final alongside Cristian Romero as Argentina’s defence took a knock.
Now, the Red Devil’s defender has sent a message to fans as he inferred that those mocking the loss of Argentina are weak.
"With a heavy heart for not having been able to bring home the cup that we all deserved, but with pride bursting at the seams for this jersey, for my teammates, the coaching staff, the executives, the medical team, the cooks, the kit men, and every single person who was involved to make all of this work in the best possible way."
"And, above all, for you, who showered us with all your love, all your strength, that passion that so defines us, and the unity of a nation that I hope endures over time. I want to congratulate Spain on their well-deserved title. I want to congratulate Spain on their well-deserved title.
"We defended our colours far beyond the pitch and shared unforgettable moments with the National Team, alongside our families and with the unwavering support of all Argentinians. It will always be an immense pride to represent you. Remember that 'the fall of the great is the joy of the mediocre.' Thank you all so much. Let's take care of our country. I love you, Argentina!"
The exact nature of his injury is not yet clear, but Martinez will now head off for a three-week break before he links with the Manchester United squad for preseason.
The Red Devils kick off their Premier League campaign with a clash away from home against newly promoted Hull City in what should be a tough clash.