The 32-year-old has not featured for his club this season after falling behind Diego Lopez in the pecking order at the Santiago Bernabeu.
Rumours surrounding his future are now certain to gather pace after Del Bosque claimed that the experienced keeper has "half-solved his future".
"I asked Iker how he was. I did not want to impose anything on him," the 62-year-old told El Larguero.
"He said it had been a difficult time, but that he was more comfortable and quiet and that he had half-solved his future.
"I hurt for the other two. I have said that with Iker we must remember, but also with [Victor] Valdes, who saved us against France in Paris and that is something I will not ever forget."
Casillas started in Spain's 2-0 win over Finland last week.