Riccardo Calafiori, Kai Havertz and Martin Odegaard scored as the Gunners secured a convincing victory at Cardiff’s Principality Stadium.
Despite the setback, Dias stressed that City are focused on the Premier League campaign and ready to respond when they face Bournemouth in their opening fixture of the 2026/27 season next Sunday.
“The way the game starts, it sets you off right away and Arsenal get comfortable into playing their game,” he told Man City website.
“In the end, this is just starting. The most important is that we’re already looking forward. We’ll be ready for the next game.
“I joined (pre-season) midway. This is the third game since I’ve been back. The feeling has been good.
“Today it’s frustrating. It was a final and we obviously wanted to win it. If there is a lesson then let it be this one because there’s a lot more coming.”