“Russian air strikes against militants in Syria are “indiscriminate” and threaten to draw Russia more deeply into the crisis” The White House says.
Spokesman Josh Earnest said Russia was carrying out random air strikes against the Syrian opposition.
Earlier, Russian Foreign Minister Sergei Lavrov said Russia was targeting the same terror groups as the US-led coalition.
He rejected suggestions that Moscow was trying to bolster the Syrian military.
Russia has said it is targeting Islamic State (IS) and other militant groups but the Syrian opposition and others have suggested rebel factions opposed to Syrian President Bashar al-Assad – the Kremlin’s ally – are bearing the brunt of the attacks.
The Syrian military has lost ground to IS and various other rebel groups in recent months.
Russian Foreign Minister, Sergei Lavrov said Russia sees “eye to eye” with the coalition on fighting terrorists.
Meanwhile, talks in Paris on Friday involving Russian President Vladimir Putin and hosted by his French counterpart Francois Hollande are expected to be overshadowed by the situation in Syria, although the meeting was called to discuss peace efforts in Ukraine.
“Carrying out indiscriminate military operations against the Syrian opposition is dangerous for Russia,” said Mr Earnest in Washington.
“It is only going to prolong the sectarian conflict inside Syria, if not make that conflict indefinite, and it also risks Russia being drawn even more deeply into that conflict.”
Mr Earnest said US and Russian officials had held hour-long talks on Thursday to discuss “deconfliction” operations, and that this was the first of a series of discussions.
Russia said it carried out its second day of air strikes on Thursday, and had hit IS ammunition dumps and command centres.
Mr Lavrov, speaking at the UN in New York, said Russia would also fight other terrorist groups including the al-Nusra Front – an al-Qaeda affiliate.
He said this position was the same as that of the US-led coalition which has been carrying out air strikes in Iraq and Syria for the past year.
“We are not supporting anyone against their own people. We fight terrorism,” he said.
“As far as I understand it, the [US-led] coalition announced Isil (IS) and other associated groups as the enemy. And the coalition does the same as Russia does.”
Mr Lavrov said the targets were selected “in co-ordination with the Syrian army”.
(Followed by BBC)