Russian foreign ministry spokeswoman Maria Zakharova said deploying additional US forces to Poland would represent a "qualitative escalation" of tensions, according to the Reuters news agency.
She said Russia could be forced to retaliate, Reuters reported.
Zakharova's comments came after Polish officials welcomed US President Donald Trump's announcement last week that Washington would deploy an additional 5,000 troops to Poland.
Trump said the move would be made in part because of his relationship with Polish President Karol Nawrocki.
Polish officials described the decision as positive news for transatlantic security and said it would strengthen Poland's defence.
The announcement appeared to reverse earlier indications from Washington that US troop levels across Europe could be reduced.
Deputy Prime Minister and Defence Minister Władysław Kosiniak-Kamysz said details of the deployment would be worked out by the Pentagon, US European Command and military planners.
He said the planning process could take between two and four weeks.
Kosiniak-Kamysz added that Poland hopes not only to increase the rotational presence of US troops but also to secure a larger permanent American military presence on NATO's eastern flank.
Trump's announcement followed reports that the Pentagon had paused the planned rotation of a US armored brigade into Poland as part of a broader review of American troop deployments in Europe.
Poland, a NATO member bordering Ukraine and Russia's Kaliningrad exclave, views the US military presence as a key pillar of its security amid Russia's war in Ukraine.