The Viola boss argued that while his players tired a little in the second half of their victory at San Siro, at no point did he feel the hosts caused them trouble
The Viola took the lead at San Siro with a deflected free kick from Juan Vargas and sealed all three points when Borja Valero pounced on a rebound with 17 minutes remaining.
Milan boss Massimiliano Allegri admitted afterwards that his side's second-half showing had been "embarrassing" and Montella has confessed the visitors never felt in any danger of losing their lead.
"In the second half we were a little tired, a little low, but there was never the feeling that the squad was suffering excessively," the 39-year-old told Sky Sport Italia.
"We deserved the victory, having played a great game. This squad is making the most of all of the resources we have, and now there is also Vargas and Ruben Olivera.
"We did well in terms of controlling the game. We didn't concede any counterattacks."
The victory propelled Fiorentina into fourth place in the Serie A standings, but they remain seven points behind Napoli and Juventus, who are two further adrift of leaders Roma ahead of their trip to Torino on Sunday.
However, while the gap to the top three is considerable, Montella refused to rule the Viola out of the title race.
"The standings are very tight - anything can happen," the former Italy international argued.