Coke scored in the second period of the La Liga clash to secure the points, but Jemez does not believe that either side did enough to deserve to win.
"I'm not very keen to talk about justice or what could have happened because sometimes you win and sometimes you don't," he told reporters at a press conference.
"It was a sham because neither the team nor the fans deserved what happened here. Sevilla have done very little, but they're going home with the points.
"The dressing room is down, but that's normal when you do the right things but aren't rewarded. The players did all they could and showed a great attitude."
Rayo remain in 19th in the table, five points from safety.