UN Secretary-General Ban Ki-moon says attacks such as the killing of an Iranian nuclear scientist in Tehran earlier this week are to be condemned.
UN spokesman Eduardo del Buey quoted Ban as saying "Any terrorist action or assassination of any people, whether scientist or civilian, is to be condemned. It is not acceptable. Human rights must be protected."
Iranian scientist Mostafa Ahmadi Roshan was assassinated in Tehran on January 11.
Iran's UN Ambassador, Mohammad Khazaee, had sent a letter to Ban and the UN Security Council asking them to condemn the assassination, which Tehran has blamed on the United States and Israel.
The United States has denied involvement in the killing and condemned it.
Israel has declined to comment.