The Viola chief praised the work of the club president in convincing the 22-year-old to remain in Florence whilst also expressing his joy at a successful transfer window
The Montenegrin had been the subject of intense speculation during the summer transfer window but a move away failed to materialise, despite links with a number of sides in Serie A and across Europe.
"The fact that he has stayed is the most beautiful thing. He has remained and is also happy," Mencucci said to reporters.
"Was he close to leaving? There were requests but it was very good of my president to convince him to stay."
A number of impressive signings, including Borja Valero, Matias Fernandez and club favourite Luca Toni, have made Fiorentina potential dark horses to compete for European football next season. And it is the capture of Toni that has caught the imagination of Mencucci.
"We expect a lot, especially because he loves Florence. We wanted to bring him back to Florence. We will be happy if he can make even more than one goal," he added.
"I'm glad to say we did a good job this summer. Montella is really great, we are very happy."