He also likened the Vatican’s opposition to the death penalty to its opposition to abortion, arguing that both constitute violations of the fundamental right to life.
The Pope’s comments are his first public remarks against the Iranian government over its protests crackdown, according to the Associated Press, in his annual speech to diplomats accredited to the Vatican.
He said: “The right to life is also threatened in those places where the death penalty continues to be imposed, as is the case in these days in Iran, following the recent demonstrations demanding greater respect for the dignity of women.
“The death penalty cannot be employed for a purported state justice, since it does not constitute a deterrent nor render justice to victims, but only fuels the thirst for vengeance.”
Francis, who has changed church teaching on the death penalty, said it is “always inadmissible since it attacks the inviolability and the dignity of the person”.
The Pope has been previously careful not to criticise the Iranian government, as he tries to bolster the relationship between the Vatican and the Shia world.
Tehran has executed four protesters since furious women-led demonstrations erupted in September following the death of 22-year-old Mahsa Amini in police custody in Tehran. She was held for violating the Islamic Republic’s strict dress code.
Two men – identified as Mohammad Mehdi Karami and Mohammad Hosseini – were hung on Saturday after being sentenced by the Iranian supreme court, and another three were sentenced to death on Monday.
According to the Iranian judiciary’s news agency Mizan, the two men executed on Saturday were convicted of killing Ruhollah Ajamian, a member of the Iranian Revolutionary Guard’s volunteer Basij force, in the city of Karaj outside of Tehran on 3 November.
At least 517 protesters have been killed since the protests began, according to Human Rights Activists in Iran, a group monitoring the unrest.
Iranian authorities have pegged the number of deaths at 300.
The executions were condemned by Western governments, including the UK, who called on Tehran to “immediately end the violence against its own people”. “The UK is strongly opposed to the death penalty in all circumstances,” British foreign minister James Cleverly said.
The United Nations urged Iran to halt all executions, saying that it was shocking that Tehran continued to hang protesters despite the international outcry. “We deplore the execution of two more protesters … following unfair trials based on forced confessions,” it said in a statement.
Additional reporting by agencies