The Englishman's perfect penalty record for the Blues was broken when Foxes’ goalkeeper, Mads Hermansen, saved his spot-kick.
Despite his first-ever professional penalty miss, the Chelsea manager praised his commitment and reaffirmed that he remains the club's primary penalty taker.
“Cole is going to miss more penalties, and the reason why is because he is the one in charge of shooting penalties,” Maresca told the Chelsea website.
“If you don’t shoot, you don’t miss. I have no doubt in the future he will miss more penalties but I also have no doubt he score more penalties.
“The penalty the other day didn’t affect him in a negative way.”
Palmer is expected to be in action when Chelsea face Copenhagen in Thursday’s Europa Conference League Round of 16 second leg.