The Red Devils defender has been included in the Azzurri’s latest squad for friendly fixtures against San Marino and Uruguay and a 2018 World Cup qualifying clash with Liechtenstein.
His absence has left Ventura short of options, with Mattia De Sciglio, Alessandro Florenzi, Emerson Palmieri and Davide Zappacosta all missing.
“I’d also add Darmian, he doesn’t have permission from United to come to us until June 5,” Ventura told a pre-match press conference ahead of Wednesday’s meeting with San Marino.
“A bizarre choice, as he’s been stopped since the Europa League final, and I think we’ve lost him for the Uruguay game too. A bizarre choice.
“We’re not going to cry though, we’ve lost many players over the months but locally we have a lot of youngsters thanks to the training camps.
“[Andrea] Conti, [Danilo] D’Ambrosio and [Leonardo] Spinazzola will be important for us in the upcoming matches.”
Ventura added: “It seems that [Andrea] Barzagli, [Leonardo] Bonucci and [Giorgio] Chiellini will all play on Saturday and I’ve spoken to all three of them.
“They’re playing on June 3 and then we play June 7, a very important friendly for us and I asked them all to give their availability.
“The response was total availability, but there’s a further step from being available to being healthy.
“We hope all three of them will be there, because [Alessio] Romagnoli and [Daniele] Rugani have physical problems.
“I want to compliment them though, they’ve been a surprise even for me. They’re an example for the younger ones.”
Italy sit second in their World Cup qualification group at present, level on points with Spain but occupying a play-off berth on goal difference.