Kiev was hit on Friday by Russian forces after it withdrew from the area two weeks ago.
Moscow said it had struck a plant used to make and repair Ukrainian missiles, including anti-ship missiles.
“The number and scale of missile strikes on targets in Kyiv will rise in response to any terrorist attacks or acts of sabotage on Russian territory committed by the Kyiv nationalist regime,” the Russian Defence Ministry said in a statement.
Kirill Kyrylo, 38, a worker at a car repair shop, said he saw three blasts striking an industrial building across the street, causing a blaze that was later put out by firefighters.
“The building was on fire and I had to hide behind my car,” he said.
Russia’s defence ministry also added it had captured the Ilyich steelworks in Mariupol, the besieged eastern port that has seen the conflict’s heaviest fighting.