Arsenal have long been linked with a summer approach for the Spain international after seeing him slip behind Diego Lopez in the Santiago Bernabeu pecking order.
They are one of several clubs reported to hold an interest, with Casillas still widely considered to be among the finest shot-stoppers in world football.
He has, however, spent his entire career to date with Real and would find it difficult to tear himself away from his home-town club.
Casillas has been asking questions about life in England, though, and Cazorla has made it clear that the World Cup winner would be welcome in north London if he does decide to move on when the transfer window re-opens.
He told Sport360: "I've told Iker I would like him to join Arsenal. But so far he has just been curious about my experience in England.
"His situation is very complicated, but he has to make a decision.
"Lots of clubs want him, including Arsenal.
"But I think it would be very difficult to leave Real because he knows what he has at Madrid, and what he could find at another club."