"To continue its presence in the international political and economic scene, the United Nations needs to undertake fundamental reforms," said Araqchi.
He was speaking at a ceremony in Tehran to mark the 68th anniversary of when the UN charter went into effect, attended by UN Development Programme (UNDP) administrator Helen Clark.
"These reforms must reflect the change in global order, particularly the growing role of developing countries, the right of nations to determine their own fates and to allow (nations) to enjoy new technologies," said Araqchi, whose country holds the presidency of the Non-Aligned Movement (NAM).
Araqchi led negotiations last week in Geneva with world powers over Iran's controversial nuclear ambitions, which have led to several rounds of UN and international sanctions damaging Iran's economy.
Western governments suspect Iran is building a nuclear military capability, a claim vehemently denied by Tehran which rejects the sanctions regime targeting its vital oil income.
"These illegal, inhumane and oppressive sanctions target Iranian citizens as well as the country's developing programmes in health, education and its fight against poverty," said Araqchi.
"Imposing such unfair sanctions against developing countries is not only contrary to the UN charter, but also exposes a serious threat to world peace and security," he said.