The 24-year-old striker has struggled with injuries this season and only recently came back onto the pitch after being out for several months with a hamstring problem.
He has scored twice in his last three league appearances and has been gradually building up his fitness in the latter half of the season.
The Austrian was wanted in the Premier League last summer and Tottenham and West Ham are interested in him ahead of the upcoming transfer window.
He has a contract until 2023 with Kalajdzic and he is expected to move on from Stuttgart next summer.
However, Mislintat stressed that the club and the player are relaxed about the situation and insisted any call will be taken after he attains full fitness.
The deal-maker told German magazine Kicker: “We are very relaxed, he is very relaxed.
“He still has a contract and has said openly that he wants to get fit first and return to the pitch before we finalise anything.”
Kalajdzic scored 16 times in the Bundesliga last season and is considered a big attacking talent in Germany.
