Acton, 25, appeared to grab the shirt of Greg Bird, lift him and push him back to the floor while he lay injured.
He challenged the grading of the offence but a Rugby Football League independent tribunal ruled it was correct and also fined him £300.
Acton has missed Leigh's last two games, which counts towards his ban.
He will now miss the Centurions' final home game of the regular Super League season against Salford on Friday and six of their seven fixtures in the Qualifiers as they bid to retain their top-flight status after winning promotion from the Championship last year.
Following the game on 1 July, Acton was charged with a Grade F offence - the most serious on the RFL's disciplinary scale, which carries a minimum ban of eight games.
Meanwhile, Wakefield forward Tinirau Arona has escaped a suspension after submitting an early guilty plea to a Grade A charge of kicking out during Trinity's victory at Widnes on Friday.
Leigh forward Jamie Action has been banned for nine games after admitting a charge of "other contrary behaviour" during his side's defeat at Catalans.