The defender is struggling with an ankle problem which ruled him out of Wednesday's Champions League win against Olympiakos.
"Koscielny looks to be definitely out for Sunday," Wenger told reporters. "It looks short for him. He couldn't absorb any test today."
"For Walcott and Gervinho a decision will be made on Saturday or Sunday," he added. "The most likely to be fit of the two looks to be Walcott."
The Gunners are currently 13th in the Premier League, while Spurs occupy sixth place.