Zaha was taunted by visiting fans over his impending transfer to Manchester United and responded by raising his middle finger towards the travelling support.
But the remorseful player later wrote on Twitter: "I also wanted to apologise for the gesture I did towards the Leeds fans in yesterday's game. Very unprofessional from me."
Zaha, who played the full 90 minutes against the Elland Road side, sealed a switch to United in January but part of the deal to take him to Old Trafford was that he remain on-loan at Palace for the remainder of this season.
Manchester United and Leeds remain fierce rivals despite the Yorkshire club's relegation from the Premier League in 2004.