According to All Market, Fiorentina contacted Motta after dismissing Grosso, but they were unable to reach an agreement due to salary and transfer demands.

Fiorentina decided last night to dismiss head coach Fabio Grosso after only three rounds of Serie A, with the team suffering three consecutive defeats. Paolo Vanoli will return as head coach and is already at Viola Park awaiting the official announcement. Paratici had previously also considered candidates other than Motta.
Motta was Paratici's first choice. Since June this year, Motta has no longer been bound by his contract with Juventus, which was originally set to run until 2027. Paratici's side had held informal contact with his team. However, negotiations stalled almost as soon as they began.
The demands put forward by Motta were difficult for Fiorentina to meet under their current circumstances. In addition to requesting a two-year contract with an option for an additional year and an after-tax annual salary of 3.5 million euros, he also clearly hoped that the club would make targeted squad adjustments starting from the January transfer window. Fiorentina had already invested 150 million euros this summer, making it difficult to meet these demands.
For this reason, the option of Vanoli's return quickly became an alternative plan. Vanoli will sign a one-year contract, with an option to extend it until 2028 if the team qualifies for the top two European competitions. The appointment is expected to be officially announced within the next few hours.