The 33-year-old sustained a damaged cruciate ligament after just 26 minutes of the Nerazzurri's 2-0 Europa League victory over CFR Cluj on Thursday, prompting fears that the forward may have possibly played his last game for the club.
However, Stramaccioni has reassured him that regardless of his setback and advancing years, he remains an indispensable team member.
"I've spent a lot of time talking to Diego, I phoned him late at night after the game and we had a long chat," he told reporters at a press conference.
"Not only are we all with him but we're all waiting for him to return. I can't envisage Inter without him next season.
"I know how much everyone here cares about him and how capable the people looking after him are. He'll have his operation today at about 14:30CET. He's in our thoughts.
"He's a fundamental part of Inter's future, my future Inter and everyone's future Inter."Switching his attentions to Sunday's match against Fiorentina, Stramaccioni acknowledged the difficulty of the clash, but remains hopeful that his side could pull clear of the Viola in the Serie A table.
"I can say this with complete confidence - the Artemio Franchi is one of the toughest grounds to go to this season," he added.
"None of the big teams have managed to win there and they've all struggled. It's a real six-pointer tomorrow, there are only four points between us and Fiorentina. It's going to be extremely tough."