Klasnic spent last season on loan at the Reebok Stadium and made a good impression on manager Coyle, who took charge in January.
The path has now been cleared for Klasnic to return to the club after his departure from Nantes was confirmed on Monday.
"He is a player that I always liked and a player we'd like to have, but there is more involved than that, such as finances, and we'll see what develops," Coyle told Sky Sports News.
"I think the world of him and he loves the football club, he's popular, but there's a little bit of water to flow under the bridge before that happens."
Asked if there had been further talks, Coyle replied: "There will be."