The US has said it shared intelligence with Ukraine about the location of the Russian missile cruiser Moskva prior to the strike that sank the warship.
But Pentagon press secretary John Kirby said in a statement on Friday that the US "did not provide Ukraine with specific targeting information for the Moskva", although he acknowledged that the US and allies routinely share intelligence with Ukraine.
"We were not involved in the Ukrainians' decision to strike the ship or in the operation they carried out," he added.
"We had no prior knowledge of Ukraine's intent to target the ship."
An American official said on Thursday that Ukraine alone decided to target and sink the flagship of Russia's Black Sea Fleet using its own anti-ship missiles – a high-profile failure for Russia's military.
According to the official, the US has provided "a range of intelligence" that includes the locations of those ships, given Russia's recent attacks on the Ukrainian coastline from the sea.
The Biden administration has ramped up intelligence-sharing with Ukraine alongside the shipment of arms and missiles to help it repel the Russian invasion.
Disclosure of US support in the Moskva strike comes as the White House is under pressure from Republicans to do more to support Ukraine's resistance – with polls suggesting Americans question whether President Joe Biden is being tough enough on Russia.
The White House has tried to balance supporting Ukraine, a democratic ally, against not doing anything that would seem to provoke a direct war between Mr Putin and the US and NATO allies.
Military and intelligence support has been increased by the US, removing some time and geographic limits on what it will tell Ukraine about potential Russian targets.
The official said the US was not aware that Ukraine planned to strike the Moskva until after it conducted the operation.