Cardiff will allow long-serving Kevin McNaughton to leave this summer along with Danny Gabbidon and Nicky Maynard.
Highly-rated Atletico Madrid midfielder Saul Niguez has signed a new five-year contract.
Former Chelsea forward Kalou is a target for Roma, but the Ivory Coast international is stalling on the switch to Italy as he holds out for a return to England.
Arsenal tried to sign Kalou on loan during the January transfer window and the 28-year-old had set his sights on moving to the Emirates this summer, but the arrival of Alexis Sanchez means Arsene Wenger is unlikely to make a new move.
The likes of Liverpool and Tottenham are thought to be monitoring Kalou's situation with the forward thought to be available for a fee in the region of £3million.
Big-spending Monaco, and Turkish duo Galatasaray and Fenerbahce, have also expressed an interest in Kalou as they look to bolster their attacking options.
Kalou, who scored 16 goals last season for Lille, is believed to favour a move back to the Premier League as his preferred destination, but Lille are reluctant to lose their top goalscorer as they hope to reach the group stages of the Champions League.