The defender singled out technical director Jason Wilcox following the loss in Spain, arguing that United needed more reinforcements to build on last season’s progress and compete against Europe’s strongest sides.
“I have to control myself a lot. But sometimes it's a reflection of how our club is at the moment, you know?” Martínez told Amazon Prime.
“We did a fantastic season last season, and now we expect more from the top, from above, you know, to bring more players to compete, because many, many teams bring many players in as well, and today also, Atlético have an amazing team, and they deserved to win today.”
Asked whether United possessed a squad capable of competing in the Champions League, Martínez was blunt.
“I expected more, honestly. I expected more.”
He was then asked whether that meant he wanted the club to invest more heavily during the summer transfer window.
“Yeah, 100 per cent,” he replied. “I expected more from our technical director. I have to be honest, you know? And also, as players, we have to do more, but it's also important when you make a strong squad to be ready for these kinds of nights.”
Martínez argued that United had laid the foundations for a stronger team last season but had not done enough to build on them. He did not identify one specific position that required attention, instead questioning the overall strength of the squad.
“In general. I think last season we did everything; we created a base to build an amazing team. But this is something to be honest and to prove something, you know?”
The Argentina international was also frustrated by the manner of the defeat in Madrid, where Pablo Barrios scored inside the opening minute before Ademola Lookman sealed the result late in the second half.
“Yeah, it's annoying, disappointing, to come here and not see my team trying to get an amazing result here. It's disappointing.”
Martínez was careful not to blame manager Michael Carrick, arguing that the club could not keep changing coaches while ignoring other areas that needed improvement.
“I don't think so. He does his best. But every season is different. You cannot say what you did last season.
“The teams know how you play, the teams know every detail, you know? And if you don't change, next season is a big problem. You cannot keep changing manager. What about other areas? I can't say more.”
Manchester United’s defeat extended their difficult start to the season, with Martínez’s comments placing renewed scrutiny on the recruitment strategy overseen by Wilcox and the club’s senior leadership.