Mr Zelenskyy said Russia was intent on destroying the once-celebrated industrial might of the Donetsk and Luhansk regions.
"We are doing everything to ensure defence," he said. "We are in constant contact with partners. We are grateful to those who really help, everyone who can help."
He also renewed calls for increased military shipments as the battle over the eastern regions is brewing.
In a thinly veiled barb at Germany, Mr Zelenskyy said the fate of the coming battle depended on “those who have the weapons and ammunition we need and are holding back. The fate of people who can be saved".
He condemned Russia’s renewed bombing campaign in Kharkiv and confirmed the official figures that five people died in strikes on the city on Sunday and 18 over the past four days.
Mr Zelenskyy shared details about his phone call with IMF chief Kristalina Georgieva earlier in the day, saying they had agreed on concrete measures to support Ukraine in the short and long terms, to help rebuild the country after the war.