Dias left Benfica for City earlier this month.
And ahead of tonight's Champions League group opener, Pep said: "Obviously we talked about the game [with the national team], a game with this dimension.
"But here is also Bernardo Silva, João Cancelo ... I have a great respect for Rúben since the first his day in the national team. He was always exemplary in the group. That shows his character.
"I'm glad he came to a club like Manchester City, to be able to evolve. I hope to leave here happier though."