The Brazilian goalkeeper was left furious after conceding a penalty during the 2-2 draw at Anfield last month, bringing down former Liverpool full-back Neco Williams inside the area as he attempted to save a Nottingham Forest attack.
Morgan Gibbs-White converted the resulting spot-kick to put Forest 2-1 ahead, before Victor Muñoz's late equaliser earned Andoni Iraola's Liverpool side a point. Still livid at full time, Alisson was filmed kicking the fourth official's electronic board as he made his way towards the tunnel.
An FA statement confirmed the punishment on Thursday.
"Liverpool's Alisson Becker has been fined £8,000 for misconduct at the Premier League fixture against Nottingham Forest on 29 August. It was alleged that the goalkeeper acted in an improper manner around the tunnel area after the final whistle. Alisson Becker has subsequently accepted the charge against him and received the standard penalty," the statement read.
The sanction arrived just days after the Premier League's Key Match Incidents Panel ruled that the penalty which sparked Alisson's frustration should never have been awarded in the first place. The panel voted 3-2 that referee Sam Barrott was wrong to give the penalty, while unanimously backing VAR Michael Oliver's decision not to send Barrott to the pitchside monitor to review the incident.
"The contact from Alisson was inevitable as a consequence of his momentum in attempting to save the ball. The contact made was not reckless and below the threshold for a penalty," the panel said. "However, the non-intervention by the VAR was unanimously supported on the basis that it was not a clear and obvious error."
The incident followed a frustrating passage of play for Liverpool, who had been trying to make a triple substitution when Forest restarted quickly from a throw-in, catching Iraola's side out of position before the penalty was awarded.
Despite the panel's finding vindicating his original protest, Alisson's post-match conduct still fell foul of the FA's separate misconduct rules, leaving the goalkeeper to accept the fine rather than contest the charge.