Russia on Monday accused Western countries of fomenting tensions in Serbia, following demonstrations over the results of the elections.
The opposition expressed objection over the results and some opposition MPs have staged a hunger strike.
The US and the EU have also condemned the results.
"The attempts of the collective West to destabilize the situation in the country are obvious," Russian foreign ministry spokeswoman Maria Zakharova told state-run news agency RIA Novosti.
She compared the unrest to the 2014 Maidan protests in Ukraine, when protesters forced a Russian-backed leader from power in what Moscow insists was a Western-backed action.
Riot police in Serbia expelled protesters who were attempting to enter the capital’s city council building on Sunday in protest of the election’s results.
More than 35 individuals were arrested during the protests, and two police officers were reported seriously injured.
Serbian opposition leader Marinika Tepic has been on hunger strike since Monday along with six other opposition MPs.
Since Saturday, Tepic has been receiving intravenous liquids daily but refuses to eat food.
"I try not to think about that (death). I don’t see this as a sacrifice. I see this as a fight, and a way that keeps me alive," she said.
"They (the doctors) are trying to maintain this condition as long as possible, because I have no intention to give up until fake elections are annulled, until they admit to electoral fraud, and until the will of the people is defended," Tepic told AFP in an interview.
"This simply needs to be done in order to alert both domestic and international audiences," she added.
But a team of international observers -- including representatives from the Organization for Security and Co-operation in Europe (OSCE) -- denounced several "irregularities", including "vote buying" and "ballot box stuffing".
Germany labeled the reported allegations "unacceptable" for a country hoping to join the European Union. The United States called on Belgrade to address the "concerns" of the election monitors, while the EU said Serbia's "electoral process requires tangible improvement and further reform".
"I would like to ask all those who are on hunger strike not to continue it ... They can organize protests every day. I'm used to protests," Serbian President Aleksandar Vucic said during a televised address to the nation on Sunday.
On Saturday, Serbian prosecutors asked the police to probe allegations of fraud.
Serbian police said on Sunday that a total of 344 complaints had been lodged on election day and that prosecutors had found elements of "criminal acts" in 18 cases.
International observers have underlined allegations of "voters living abroad being organized and bussed by the ruling party to cast the ballots for local elections in Belgrade".
Tepic has accused Vucic of overseeing the scheme.
"I think that (Serbia) is the only country in the world with a phenomenon of electoral migrants," Tepic said.
Vucic denied the accusations. "We will defend the electoral will of the people and there is no doubt about that," he said.