The 23-players in the European champions' squad, including striker Fernando Torres, midfielder Xavi and goalkeeper and captain Iker Casillas, met up at the Las Rozas training facility outside Madrid on Monday.
A spokeswoman for the Spanish football federation said Del Bosque had told them they were not allowed to use the sites at any of the team's training camps or at the World Cup in South Africa starting on June 11.
There are several examples of players and other athletes getting themselves into trouble using the sites.
England striker Darren Bent apologised to Tottenham Hotspur chairman Daniel Levy last year about comments on Twitter relating to his transfer to Sunderland and his account was closed down.
Real Madrid's Brazilian playmaker Kaka said this season he was going to shut his wife's Twitter account after Spanish media reported she had used it to criticise the La Liga club's coach, Manuel Pellegrini, for not giving her husband more playing time.
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