The Germany international has been sidelined since September with a knee injury but made the bench for his club's Coppa Italia semi-final win over Udinese in midweek.
And Gomez, who joined the Viola from Bayern Munich in the summer, is now in line to make his eagerly awaited comeback in Saturday's Serie A clash with Inter at the Artemio Franchi.
"Mario is training well. He's enthusiastic about playing but he's still not physically in top condition," Montella told a press conference on Friday.
"Hopefully he'll be able to play a little part tomorrow [Saturday] but we'll have to wait and see.
"This game's a game in and of itself. It's a whole different story to the match last year."
Fiorentina's 2-0 win over Udinese on Tuesday saw them book a place in the Coppa Italia final against Napoli.
Montella, however, says his side are feeling the effects of the victory and warned his players that they need to remain grounded.
"The team is a bit tired but it will be essential to restore our physical and mental well-being," he said.
"It's going to be a difficult game though because Inter have some great players who can really damage us.
"Hernanes has come in and has improved them already. He's a strong player and brings an element of unpredictability.
"Of course, we're on a high after the cup win but we can't be too euphoric. We want to play with confidence, but we can't be overconfident."