"Potentially, this is extremely dangerous, it will mean bringing the conflict to a whole new level, which, of course, will not bode well from the point of view of global and pan-European security," Kremlin spokesman Dmitry Peskov told reporters.
Ukrainian President Volodymyr Zelensky on Thursday heaped pressure on Western allies to provide Kyiv with more heavy weapons to fight Russia on the eve of a key donor meeting.
On Friday, the United States will gather its allies at its airbase in Ramstein for a new round of talks on backing Ukraine militarily.
"There are times where we shouldn't hesitate or shouldn't compare," Zelensky told the annual World Economic Forum gathering in Davos via video-link.
"When someone says 'I will give tanks if someone else will also share tanks'... I don't think this is the right strategy to go with."
Peskov spoke after Moscow's ambassador to the United States Anatoly Antonov said Russia would retaliate if Ukraine uses Western-supplied weapons to target Russia or the Crimea peninsula, annexed from Ukraine in 2014.
"It should become obvious to everyone: no matter what weapons the Americans or NATO supply to the Zelenskyy regime, we will destroy it," he said, referring to Ukrainian President Volodymyr Zelensky.
"It is simply impossible to defeat Russia," he said in comments released by the embassy.
He said that US rhetoric over Ukraine was becoming "more and more belligerent."
By insisting that Crimea was part of Ukraine and saying that Kyiv can use US weapons to protect its territory Washington "is essentially pushing the Kyiv regime to commit terror acts in Russia," Antonov said.