The United States and the European Union have sanctioned Iran over its drone programme, alleging it had supplied Moscow with unmanned aerial vehicles during Russia's invasion of Ukraine - a charge Tehran denies.
On Wednesday, during his daily speech, Zelensky said Tehran's "support for evil cannot be denied" and appealed directly to Iranians, asking: "Why do you want to be accomplices in Russian terror?"
In response, Iran's foreign ministry spokesman Nasser Kanani said Zelensky's "repetition of false claims" against the Islamic republic was "in harmony with the propaganda and media war of the anti-Iranian axis".
"It is done with the aim of attracting as much military and financial aid from Western countries as possible," Kanani said.
Ukraine, he added, had "specific political goals and motives behind such accusations" and was "avoiding expert negotiations with the Iranian side to investigate the claims".
Russia has reportedly used 1,160 Iranian-made Shahed kamikaze drones in attacks against Ukraine.
"Even though we have learnt to shoot down most of your kamikaze drones, there are still hits," Zelensky said Wednesday.
"When an Iranian drone kills a pregnant Ukrainian girl and her husband in their home, why do you, mothers and fathers in Iran, need this?" he added.
"When your Shahed hits a dormitory with our students, people die, a fire starts, rescuers arrive, and in a few minutes a second Shahed hits."
Russia invaded its neighbour in February 2022, sparking the biggest conflict on European soil since World War II.