Luis Enrique has hit out at Robert Moreno for being "disloyal" due to the latter's demand that he remain as national team coach during next year's European Championships.
The former Barcelona manager stepped down from the position in June to take care of his daughter, who passed away with bone cancer in August.
In his place, Moreno took charge of nine games, winning seven of them as Spain comfortably qualified for Euro 2020.
Speaking at a press conference after returning to the Spain role, Enrique told the Daily Mail: "I am the only reason why [Moreno] is not in my staff. The fall-out comes from a meeting we had on September 12 at my home. It's the only day we had contact.
"We had a 30-minute meeting and I understood that he wanted to take charge of the team in the Euros [next summer] and to then go back to being my No 2 afterwards. And in that moment I try to put myself in the other person's shoes. I understand that he wanted to take the opportunity of his life. I understand that he is ambitious and that's a quality to admire but, for me, that's also disloyal and for me that is a defect.
"I understand his position but I don't share it and I would not have done that. I said I wanted to come back. I then called every member of my staff asking for their opinion."
Enrique, who became Spain manager after the 2018 World Cup, enjoyed a successful period at Barcelona, winning the treble in 2015.