The 37-year-old still has one year left to run on his contract at Porto, but it had been claimed that he could return to Spain before hanging up his boots.
Casillas, though, has said that Porto are likely to be his final club, with the 167-time Spain international ruling out a move to his homeland.
"It would be nice to have had only a few clubs in my career," Casillas told RTP. "I spent a large part of my life at Real Madrid, which is the best club in history.
"But I came to Portugal and joined a strong team like Porto, so that makes me very happy. I'd like to finish my career with Porto and go to the end of my contract."
Casillas made over 700 appearances for Real Madrid between 1999 and 2015 before joining Porto, and has since played over 100 times for the Portuguese giants.