Messi scored a superb first goal since his summer move from Barcelona as the French side gained some revenge for last season’s semi-final loss with a 2-0 victory in their group clash on Tuesday.
The Argentinian exploded into life in the 74th minute at the Parc des Princes, running from halfway and finishing from the edge of the box after playing a one-two with Kylian Mbappe.
Despite the defeat, which saw City slip to third in Group A behind Bruges and PSG, defender Dias felt the Premier League champions could take a lot of positives.
The Portuguese said: “If you want to be at the top, if you want to be number one, you need to play against some of the best.
“I would say that is the best you can have. It is always challenging and it is always good to be able to prove yourself to yourself. As a team it is always special to play these games.
“We are disappointed because we demand everything we can from ourselves, individually and collectively. If we don’t take a win we will never be satisfied, even though we have made a good game.
“We know in the ultimate instant what matters is winning but the team performed and we created chances. We will take the ‘goods’ and the ‘bads’ and we will get better.”
Messi had been a doubt ahead of the game but grabbed the headlines with his sublime strike, which added to an early effort from former Everton midfielder Idrissa Gueye.
The six-time world player of the year had made a slow start to his PSG career, failing to find the net in his first three appearances and being hampered by fitness problems. There had been questions over whether the much-vaunted front trio of Messi, Neymar and Mbappe would click but there may be fewer doubts now.
“I hadn’t been able to play recently and this was only my second game in this stadium,” Messi, 34, told Canal+. “I’m adapting to my new team.
“The more we forwards play together the better our relationship will be. We all need to grow together and improve and keep giving our best.”
Despite the result, City could reflect on a strong performance. They ensured Gianluigi Donnarumma was the busier goalkeeper and also hit the bar twice in quick succession through Raheem Sterling and Bernardo Silva.
Messi said: “They were great opponents but it was very important for us to win the match after our draw against Bruges.”
City are back in action against title rivals Liverpool at Anfield on Sunday, their third tough away game in just over a week stretching back to last Saturday’s victory at Chelsea.
Dias does not believe the frustration in the French capital will have any bearing on the trip to Merseyside.
He said: “It affects nothing. We know what we are capable of and we know our identity. We know what we need to do at Anfield to win.
“It is a loss and we are frustrated but that is the good habit of being a top team. We will take it but in no time will be there again.”