Matri has been without a club since being released by Sassuolo in January after spending the first half of the 2019/2020 season at newly-promoted Brescia, where he failed to find the back of the net in eight league appearances.
Matri also represented the likes of Cagliari, Fiorentina, Genoa and Lazio in a career that also saw him earn seven caps for the Italian national team, scoring once.
He won three Serie A titles in two spells with Juventus and also scored the winner in the 2015 Coppa Italia final for the Old Lady against Lazio.
"I can say that I made my dreams come true. When I started this sport, I didn't think I would have a career like I did and would win three league titles," Matri told Sky Sport Italia.
"I can't complain about how it went, but now I'm at the end of the road. I made the decision after seeing how the first six months went with Brescia.
"I lost some motivation and didn't feel good on the pitch. I no longer felt like playing football and it's not in my character to stay at a club where I cannot give what is needed.
"After I was released, I didn't receive many offers and I wasn't convinced by them.
"I preferred avoiding making a fool of myself. I will miss my life as a footballer, but only a big offer could get me going again."
