Russia has condemned foreign powers for backing a Venezuelan opposition leader who declared himself interim president, calling it a bid to "usurp power".
Moscow says the move violates international law and is a "direct path to bloodshed".
Kremlin spokesman Dmitry Peskov said: "We consider the attempt to usurp sovereign authority in Venezuela to contradict and violate the basis and principles of international law.
"Maduro is the legitimate head of state."
A Russian foreign ministry statement said Mr Guaidó's declaration was a "direct path to lawlessness and bloodshed", adding: "Only Venezuelans have the right to determine their future.
"Destructive outside interference, especially in the current extremely tense situation, is unacceptable."
Russia also warned that any US military interference would amount to "adventurism which is fraught with catastrophic consequences".
The stance puts Russia at odds with United States President [https://www.radionz.co.nz/news/world/380857/trump-backs-venezuela-opposition-leader-juan-guaido-as-president Donald Trump's announcement earlier, that he recognises the leader of the opposition party, Juan Guaidó, as interim president of Venezuela.
Mr Guaidó, the Venezuelan opposition leader declared himself interim president during mass protests on Wednesday, winning the backing of Washington and neo-liberal Latin American nations.
His announcement prompted socialist Maduro, who has led the oil-rich nation since 2013, to sever diplomatic relations with the US.
Venezuela is the most significant US foe in Latin America, and a close ally of Moscow, which has become a lender of last resort for the unstable country, as its socialist-run economy implodes.
Russian lawmaker Franz Klinzevich on Thursday warned Moscow could wind up its military cooperation with Venezuela if Maduro, whom he called the legitimately-elected president, was ousted.
Trump formally recognised Mr Guaidó shortly after his announcement and praised his plan to hold elections.
The United States is seeking to ensure that Venezuelan oil revenue goes to Mr Guaido.
The US wants to further cut off money from the increasingly-isolated President Nicolas Maduro, whose administration is already struggling with unpaid bills and creditors demanding payment.
The National Security Adviser, John Bolton, said the oil revenues should go to the legitimate government, led by Mr Guaido.
However, he said the process was "very complicated" and officials were still studying how this could function.
Statements from Canada and a slew of right-wing Latin American governments, including Venezuela's neighbours Brazil and Colombia, backed Mr Guaido as interim president.