Cassano has revealed he recommended the Spaniard to Fiorentina after Raffaele Palladino, now in charge of Atalanta, left the job at the end of last season.
He told Cronache di Spogliatoio: "I sent a message to Daniele Pradè , one way or another, etc.
"I told him: 'Since Palladino has left—I wrote to him the next day—do everything you can to go and get Andoni Iraola from Bournemouth'."
Cassano added, "He also contacted him, he told me: 'I spoke to him, it's complicated for him to come.' Then he probably also told me to make me happy, I don't know.
"But I gave him this advice, because it's incredible that so many teams always go for Italian or low-level coaches. And I wrote to him: 'Go get Andoni Iraola, he's a phenomenon.' He has a great personality, he makes teams play like a European team."
Iraola, for his part, confirmed Cassano's claims.
"I don't know, maybe Antonio still has his contacts in Madrid, right? Maybe they told him something," he said.
"I've never coached big clubs, I haven't won many titles. But I'm very happy with my career as a coach. And that a player like Cassano speaks like that about me. Yeah, what can I say? He's played for the best clubs in the world, so he knows the game at a high level, and I appreciate that."