The 26-year-old has long been a target for the newly-promoted side, and currently plays in China for Liaoning Whowin.
A former Mainz, Cologne and Werder Bremen striker, Hannover feel the powerful Ujah would be a welcome addition, but admit they may be priced out of a move.
Heldt said on Own Goal Nigeria: “Let’s see if it works, we need patience.
“We are not going to push beyond our limit for any player.
“We can’t afford to discredit the ones we have because of one player.”
Ujah, who joined the Chinese Super League side for €13m last year, is contacted at the club until 2019.
He has scored five goals and made a further two more in his 13 matches played this season.