Borini was in the senior squad for last summer's European Championships.
"Mangia was fundamental in this decision," he told Rai Sport. "The Coach waited until my injury had healed, and then called me up.
"Every time I hurt myself and wondered if I would return to the squad.
"I have always been a part of this group and I wanted to end on a high.
"I am no longer under 21, so I'm thankful to Mangia."