Spain have won three consecutive major championships and they travel to Georgia on the back of a 13-match unbeaten run, including the 4-0 victory over Italy in the final of Euro 2012.
But Del Bosque is anxious that Spain take nothing for granted in a group that includes France, Finland, Belarus and Georgia.
"The World Cup does not start in 2014 but now, here against Georgia in Tbilisi. To defend the title that Spain won in Johannesburg we need to first qualify for Brazil," Del Bosque was quoted as saying in AS.
Spain warmed up for the Georgia clash with a 5-0 friendly victory over Saudi Arabia on Friday, a match which saw David Villa make a goalscoring return to international football following injury.
Georgia opened their qualification campaign with a 1-0 win against Belarus courtesy of a second-half strike from Tornike Okriashvili.
Belarus travel to France aiming for a repeat of their victory in Paris at the start of their Euro 2012 qualifying campaign.
Les Bleus head into the game on the back of a 1-0 victory over Finland, secured by a goal from Abou Diaby on his return to international football.
Injury-plagued Diaby has been out of the France picture for more than a season and he managed just four appearances for Arsenal last season.
But he made an immediate impact on his return against Finland and coach Didier Deschamps is glad to have him fit and fighting again.
"He is an all-round midfielder. He wins the ball, but also carries it forward very well and he can score. Obviously I want to have him available," Deschamps said.
"I did not need to be reassured because I have been seeing him play at Arsenal. He has a lot of qualities."