The Austrian international played a key role for his side last season, scoring 6 goals in 15 Bundesliga games to help Stuttgart avoid relegation from the Bundesliga.
Despite preserving his club's place in the top flight, Kalajdzic has been linked with a move away from the Mercedes-Benz Arena, with his contract set to expire next summer.
According to Sky Sports News, Manchester United are interested in signing the striker as they look to strengthen in the final third.
The report states that the Red Devils have already held talks to discuss a potential transfer, although no offer has been made for the 25-year-old.
If United decided to move for the striker then they could face competition from other Premier League Clubs, with West Ham United, Brighton & Hove Albion and Southampton all credited with showing an interest.
Kalajdzic, who has scored 24 goals in 57 appearances for Stuttgart, is reportedly keen on a move to the Premier League.