He told a Japanese newspaper he would not send his troops to the frontlines without more tanks, artillery and Himars rocket launchers.
In an interview with Yomiuri Shimbun, he said the situation in eastern Ukraine was "not good".
"We are waiting for ammunition to arrive from our partners," he said.
And when asked about the expected counter-offensive, he said: "We can't start yet, we can't send our brave soldiers to the front line without tanks, artillery and long-range rockets."
He added: "If you have the political will, you can find a way to help us. We are at war and can't wait."
There has been talk for some weeks of Ukraine launching a spring offensive against Russian forces. Ukrainian commanders have hinted it might be imminent. Oleksandr Syrskyi, commander of Ukraine's ground forces, said this week it might come "very soon".