Israeli striker Hemed, 30, scored the winning goal before his tussle with Newcastle defender DeAndre Yedlin. Brighton manager Chris Hughton. cleared Hemed of any blame in an incident missed by the match officials.
Upon being charged by the FA on Monday, Brighton submitted an appeal which Hemed lost on Wednesday.
Hemed wrote on Twitter: "I accept the decision against me but do not agree with it and and I am devastated to miss three matches. I would never go out injure a fellow professional on purpose, and those of my friends and teammates who know me, know that is not in my nature.
"I will use the time to get fitter, stronger and come back hungrier to score more goals for Brighton in the Premier League."