File photo: Iran s Supreme Leader Ayatollah Ali Khamenei speaks in Tehran. AFP
Western nations have pushed "the people of Ukraine to the frontlines in order to fill the pockets of American arms-manufacturing companies", Khamenei said during a meeting with senior clerics and seminary students in Tehran.
He said "the predatory" and "colonial" motives of the West have pushed Ukrainians to fight and be killed to serve "the interests of Western arms production and sales companies".
Ukraine's Western allies have sent weapons worth tens of billions of dollars (euros) to help Kyiv counter the deadly invasion Russia launched in February 2022.
Kyiv and many of its Western allies have accused Iran of sending weapons to Russia for use in the conflict, accusations that Tehran has repeatedly denied.
On Wednesday the G7 nations -- Britain, Canada, France, Germany, Italy, Japan and the United States -- pledged to offer "enduring" military support to Ukraine to fight Russia's invasion.
Both Tehran and Moscow are under international sanctions that restrict trade, and have sought to boost cooperation in key areas and bolster their economies.
The United States has accused Tehran of supplying Moscow with drones and of helping Russia to build a drone factory.
Iran rejects the allegation, with foreign ministry spokesman Nasser Kanani saying last month that "the Islamic republic does not support any side in the Ukraine war".
"We deny any accusations regarding the export of arms to Russia for use in the war against Ukraine," Kanani said.