The goalkeeper says he got to the ball before the advancing Harry Kewell in the 75th minute at Elland Road and feels that he was fouled by the Australian.
"I got the ball," said Kasey afterwards. "I always thought it was a foul if you had control of the ball and it gets taken out of your hands.
"What happened after that I have no idea. That's the frustrating thing - I know, Tony Gardner knows that I definitely held the ball.
"There are always angles and people see things differently, but Simon went through at the end and there was no call what so ever. I think that's where it gets frustrating.
"Aside from all that I think we responded tremendously well after conceding the first goal. The team played great and I was very happy throughout the game."
Kasey went on the add that the team will not give up on a European place until it is deemed mathematically impossible.
"As long as there is a mathematical chance you keep fighting. You win more games, we've got some good home games coming up - win those and see what happens."
Kasey Keller insists that he claimed the ball in the incident that led to Leeds being awarded a match-saving penalty on Saturday.