The Ivory Coast international joined les Dogues on a free transfer from Chelsea in the summer, but has reportedly been the brunt of the fans' ire as they labour midtable in Ligue 1.
However, the Spanish coach believes that Kalou has been hampered by an injury that spoiled a promising start in Lille colours.
"With regard to Salomon, he had been the most dangerous player since the season started, but then he injured his thigh," he told Le Dauphine Libere.
"When he came back against Bordeaux, he was in good shape, but it was only natural that he suffered against Bayern Munich [in the Champions League].
"Against Valenciennes last weekend, he showed his abilities and was involved in both goals. We need to give time to the players who join us."
Kalou has one goal to show from his five appearances this season.