Kremlin spokesman Dmitry Peskov said Russia would retaliate if its frozen assets were seized.
The US House of Representatives approved a series of foreign aid bills on Saturday, including measures to seize frozen Russian assets to finance Ukraine.
"This is a seizure of state property," Peskov said on Monday, stressing that it was "illegal" and would be met with "some kind of retaliatory action" or lawsuit.
"If such measures are implemented, many countries and investors will think 10 times before investing in the US economy or concentrating their assets there," the spokesman said, adding that the move would ultimately harm US economic interests.
