Del Bosque stepped down as Spain boss in the wake of their last-16 exit at Euro 2016, having previously guided them to 2010 World Cup and Euro 2012 glory.
Guardiola is not among the candidates to take the vacancy following his recent arrival at City, but the Del Bosque has backed him to lead his country later in his career.
"Guardiola is the best coach around at the moment, there is no doubt about it. He got a great education and has since only developed," Del Bosque told Suddeutsche Zeitung.
"In the past, we brought in coaches from abroad. Now our coaches are the ones moving abroad. We are proud of someone like Guardiola. We could never have imagined this a few years ago.
"I don't see any reason why Guardiola could not coach Spain. Of course, he is Catalan, but is it not our job to unify people? It would be great if football could help bringing Catalunya and the rest of the country closer again.
"He would probably not make as much money as Spain coach as he makes at a club, but I don't think that's important for people who have already made a lot of money."