The October 20 election, in which pro-European President Maia Sandu is seeking reelection, is becoming increasingly heated. The poll is being held alongside a referendum on pressing for European Union membership and officials accuse pro-Kremlin groups of offering cash for voters to reject the EU plebiscite.
National police chief Viorel Cernauteanu said instances of vandals hurling paint at public buildings last month were a precursor to more serious acts.
"We are looking at the intentions of such people and we are not just talking here about destabilising the situation in the country or mass disorder," he told TV8 television.
"They are pursuing more ambitious goals, up to and including the seizure of state institutions."
He said those behind the vandalism were being paid 5,000 euros ($5,500) for a single incident.
"It is clear that Russia is financing this. It is not simply happening just like that," he said. "The stakes are high."
On Thursday, Cernauteanu said more than 130,000 Moldovans had been bribed by a Russia-managed network to vote against the referendum and for Russia-friendly candidates. He said about $15 million had been transferred in September alone.
Fugitive pro-Russian businessman Ilan Shor, who was convicted last year in absentia for his role in the theft of $1 billion from Moldovan banks, has led the campaign against the referendum, openly offering to pay anyone voting "no".
Moldovan law enforcement agencies said last week they had detained two young men following the paint-hurling incidents. They said the men were part of a group of 20 who had been trained in Moscow.
A Moldovan court sentenced seven people this week to prison terms of up to 3-1/2 years for mass disorder during anti-government protests last year.
Sandu, who has accused Russia of trying to topple her, leads opinion polls with 27% support. Renato Usatiy, who calls for good relations with the West and Russia is credited with 13%, while sacked prosecutor general Alexandr Stoianoglo, who is backed by the pro-Moscow leftist opposition, is on 11 %.
Surveys show backing for EU membership in the referendum at 56% among decided voters, with 34% opposed.
