Iran has fiercely denied that it executes juvenile criminals or stones people to death, as some human rights groups have alleged.
Jamal Karimirad said stoning sentences were no longer carried out
"In the Islamic republic, we do not see such things being carried out," said judiciary spokesman Jamal Karimirad.
He described reports that such punishments were continuing as foreign propaganda against the Iranian state.
The UN General Assembly recently censured Iran for "continuing violations of human rights".
It condemned the country's record on torture, public executions, floggings and discrimination against women.
Last month, Amnesty International said it feared Iran was about to carry out a sentence of stoning against a woman convicted of adultery.
'Distorting Iran's image'
It urged Tehran to grant a last-minute reprieve to the woman, Hajieh Esmailvand. Iran said the sentence was deferred for consideration by the pardons commission.
But diplomats and rights groups say there have been recent executions of people under the age of 18.
Amnesty says that in 2003, Iran was second only to China in the number of executions it carried out.
Iranian law specifies exactly how stoning should be carried out, saying stones must be small enough not to kill instantly.
But Mr Karimirad said that even if such sentences were passed by lower courts, they were overruled by higher courts and "no such verdicts have been carried out".
"Bringing up the issues of stoning and the execution of under-18s comes from outside the country and is aimed at distorting the image of the Islamic republic," he said.