Casillas ended a 25-year stay at Madrid in 2015, departing his boyhood club for Porto after winning five La Liga titles and three Champions League crowns.
While Madrid have denied forcing Casillas out, his farewell paled in comparison to Iniesta's at Barcelona and Torres' at Atletico Madrid earlier this month.
Casillas, 37, said he would have no issues returning to Madrid in the future, but accepted his farewell was mishandled by the European champions.
"If Real Madrid call me, I couldn't say no to return to the club in the future," he said on Wednesday.
"I saw the Iniesta and Torres farewells and, well, my situation was another, different then in Real Madrid.
"In the future there will be reconciliations and there won't be any problem. Everybody would love a farewell like those ones, but I'm not all the day focused on that."
Casillas played 16 seasons at Madrid, while the 167-time Spain international helped his nation win the 2010 World Cup and European Championships in 2008 and 2012.