The Real Madrid striker was sidelined for about three months this season after sustaining a serious knee injury during his side's 3-0 defeat against arch-rivals Barcelona in November.
"This could be my last World Cup and I have the desire to play a good tournament," the 28-year-old Raul was quoted as saying by Spanish paper Marca.
"I am getting better everyday, restoring my shape and pretty sure I will be fit for the World Cup."
Raul also played down the importance of the goal drought he suffers since coming back from injury.
He added: "I am confident I will score and when I get my first goal, several goals will follow."
The Real skipper found the net only five times before his long layoff and couldn't stretch his tally after returning to action.
Raul will lead Spain's attacking line in the World Cup alongside Atletico Madrid's Fernando Torres and Valencia's David Villa, who finished the domestic season as La Liga's second scorer following Barca's Samuel Eto'o.
Spain are drawn in Group H that also includes Saudi Arabia, Tunisia and Ukraine.