Manchester City boss Guardiola was linked with Juve last year, as was Pochettino while still in charge of Tottenham.
Cassano declared: "Juventus tempted Guardiola last year and then went for Pochettino. They got nothing and ended up hiring Sarri.
"It was a different choice regarding the style of play but now they have to stay with him."
Sarri was hired by Juve after he left Chelsea at the end of last season.