Jacoby appealed, and his penalty was upheld after a hearing Friday.
Jacoby was accused of pinning umpire Doug Eddings against a wall in a dugout tunnel after a loss at Boston on April 29. Jacoby said he was "wrongly accused" and wouldn't apologize, adding the penalty was "very biased, harsh, and unfair."
World Umpires Association attorney Brian Lam said in a statement Saturday that "emotions often run hot after games, and people sometimes do terrible things that they later deeply regret."
Lam said MLB's decision reinforced that no one can be allowed to attack a game official.
"Those involved, even those who struggle to accept responsibility for their actions, have committed to ensure that such regrettable incidents do not occur in the future, and we take them at their word," Lam said.