"(We) agreed that our forces have the strong potential to advance on the battlefield and inflict significant new losses on the occupiers," he said in his video address.
There have been no major breakthroughs on front lines since Russian forces seized the last two Ukrainian-held cities in eastern Luhansk province in late June and early July.
Russian forces are now focused on capturing all of neighboring Donetsk province on behalf of separatist proxies who have declared two breakaway mini-states covering the wider industrialized Donbas region.
Kyiv hopes that gradually increasing supplies of precision, longer-range Western weaponry, such as U.S. High Mobility Artillery Rocket System (HIMARS), will allow it to counter-attack and recapture lost eastern and southern territories.
Russia's defense ministry said on Friday its forces had destroyed four HIMARS systems between July 5-20. Reuters could not verify the assertion.
Ukraine has accused the Russians of intensifying missile and rocket strikes on cities in recent weeks in a deliberate attempt to terrorize its population.
Cities and towns have been devastated by Russian bombardment during the conflict, with some far from front lines hit by missiles. Moscow denies deliberately firing on civilians and says all its targets are military.
However, there is a high chance of Russian longer-range weaponry missing their intended targets and causing civilian casualties because Moscow is increasingly using long-range air-defense systems to compensate for a shortage of ground-attack missiles, according to British military intelligence.
Such air-defense systems, tipped with smaller warheads to shoot down aircraft and missiles, are not likely to be able to penetrate hardened military structures on the ground and their crews will have little training for such missions, Britain's defense ministry said in an intelligence update on Friday.
Kyiv and the West say Russia is mounting an imperialist campaign to reconquer a pro-Western neighbor that broke free of Moscow's rule when the Soviet Union collapsed in 1991.
The biggest conflict in Europe since World War Two has killed more than 5,000 people, driven more than 6 million out of Ukraine and left 8 million internally displaced, according to the United Nations.