The Asturian resigned in June to spend time with 9-year-old Xana, who died of a rare form of bone cancer last Thursday.
Luis Enrique’s former assistant Moreno is preparing for his first games in charge of Spain since being officially appointed, having managed the team on three occasions during his predecessor’s absence.
“I consider Luis a friend and ahead of everything is friendship,” Moreno told a news conference.
“If one day he wants to return, I would be delighted to take a step to the side and work with him.”
Spain face Romania on Thursday and then host the Faroe Islands in Gijon on Sunday in qualifying matches for the 2020 European Championship.
“It has been a difficult week,” added Moreno. “We will try to provide some small joy in the middle of a very bad moment. It is the only thing that we can do.”
Spain are top of qualifying group F with four wins from four matches.