Royal Spanish Football Federation (RFEF) president Luis Rubiales insisted there was "no mutiny" from the players after the sacking of Julen Lopetegui.
Lopetegui was stunningly sacked as Spain coach on Wednesday, just a day before the beginning of the World Cup.
It came just a day after it was revealed Lopetegui was taking over as Real Madrid boss, news Rubiales says he only found out minutes before the announcement.
Amid reports the players had pleaded for Lopetegui to remain in charge, Rubiales insisted the squad were happy ahead of the showpiece tournament.
"I have listened to everyone, but the decision is mine," he told El Partidazo de COPE.
Spain players with Hierro 'to the death'
"The players are completely determined to make a great World Cup. There is no mutiny, the players are doing very well."
Real Madrid great Fernando Hierro will lead Spain – who face Portugal, Iran and Morocco in Group B – at the World Cup.
Rubiales said the appointment of the 50-year-old had been well received by the players.
"The players have welcomed Hierro and have told me they will be with him to the death, with [Sergio] Ramos very well, acting as captain," he said.
Spain begin their campaign with a clash against Portugal in Sochi on Friday.