But De Witte said talks have been halted, with LOSC not bidding enough for the Canada forward.
Lille offered €25m for David which is below the asking price of €30m that the Belgian club want.
“The contacts [with Lille] came to a halt this week, but other clubs are still interested,” he told De Zondag.
“With much better offers even, including Leeds. But again, I will do everything I can to keep him.”
Gent want to hold on to David after his 23-goal season, but the level of interest will make it difficult.
Leeds would have to break their club-record transfer fee (£18m for Rio Ferdinand in November 2000) to land David.