The Ivory Coast international netted 13 times last term, and Lopez has now confirmed Barcelona are one of several leading clubs showing an interest.
"It's true. Several big clubs are interested in him," he said, per RMC Sport.
"Some clubs have contacted us directly after the transfer window to know what the state of play is."
While Lopez says he wants to keep the star until the summer, he admits that a number of players may have to leave in January, due to the club's precarious finances.
"I want him to stay until the end of the season as a minimum," he said.
"We'll certainly sell (players in January). We're starting to have players who are not happy with their game time.
"If we can, we're going to sell players who have good qualities but less game time. We've got five centre-backs, for example."
Lille are currently third in Ligue 1, five points behind leaders PSG.