Ramos: Spain are still 'together' amid managerial drama
Loptegui was removed from his post on Wednesday following Tuesday's announcement he is to take over as Real Madrid coach.
Fernando Hierro has been drafted in as replacement for the tournament, with Spain's first Group B match taking place on Friday against neighbours Portugal.
But Ramos has moved to quell any notion that 'La Roja's chaotic preparations for the World Cup have had an impact on the unity in the camp.
He posted on Twitter: "We are the national team, we represent a shield, the colours, the fans, a country.
"The responsibility and commitment are with you and for you. Yesterday, today and tomorrow, together: #VamosEspana"
Hierro, who won five LaLiga titles and three Champions Leagues in a glittering Real Madrid career, has somewhat limited experience as a coach.
He was an assistant to Carlo Ancelotti at Madrid during the 2014-15 season before taking charge of second-tier Oviedo in 2016-17.
Hierro has been working as Spain's sporting director since last November.