He is accused of grabbing one policeman while being driven to a police station and elbowing another.
After hearing evidence in his trial, he denied the charge.
"They didn't ask me anything about fighting police; they asked me where I served in the Marine Corps, what deployments I was on", he said.
Reed told journalists after the verdict that "this is completely a political case", amid suspicion he is being used as a pawn in a potential prisoner swap.
Reed and Tsybulnik have both disputed the officers' statements, with Reed saying he could not recall anything from that night. Reed's team also alleges regular mistreatment by Russian authorities.
Trevor Reed was charged in August 2019 with assaulting the officers who were driving him to a police station after picking him up following a night of heavy drinking at a party.
Reed's mother Paula said that her husband Joey will remain in Russian Federation for the time being as the case is appealed.
Reed's parents say the case against their son is marked by discrepancies, including missing evidence and contradictory accounts by police officers.
After his sentencing, Reed spoke to the courtroom from the locked metal cage where defendants sit throughout a trial, criticizing what he sees as the political nature of the case and urging the USA government to intervene on his behalf.
In his final statement to the judge, Reed said, "I think it would be unethical and immoral to plead guilty to a crime I didn't commit".
In June, Russia sentenced another United States citizen, Paul Whelan, to 16 years in a high-security prison on spying charges. Police said Reed was detained for public drunkenness after leaving a party heavily intoxicated with his girlfriend, Alina Tsybulnik, and one of her co-workers.
CCTV footage did not show the police vehicle swerving while on its way to the station, as the officers had claimed.
Sullivan told NBC News that part of the reason was that he hoped this might prevent Reed's case from being overly politicized.
Reed's father Joey (pictured standing) blasted the "corrupt" trial and said he intends to appeal to Vladimir Putin. Officers from Russia's domestic intelligence agency, the FSB, questioned Reed without an attorney or a translator present, Tsibulnik told an ABC reporter.
Reed's case has attracted attention owing to the lengthy sentence faced by a U.S. citizen and speculation in Russian and USA media that Reed could become part of a prisoner swap.