Tripoli, 13 September:

Both UN Secretary-General Ban Ki-moon and the Security Council have issued statements condemning the the attack on the United States of America’s diplomatic mission and the killing of Ambassador Chris Stevens and three other US diplomats.

In its statement, the UN Security Council condemned "in the strongest terms" what it said was a "heinous" act.  The 15 members "expressed their deep sympathy and sincere condolences to the victims and to their families".
The Security Council also condemned  the attack on the United States Embassy in Cairo the same day.

Calling on Libya "bring perpetrators of these acts to justice", the  Security Council said that such acters were unjustifiable "regardless of their motivations".

Members of the Security Council "recalled the fundamental principle of the inviolability of diplomatic and consular premises, and the obligations on host Governments, including under the 1961 Vienna Convention on Diplomatic Relations and the 1963 Vienna Convention on Consular Relations, to take all appropriate steps to protect diplomatic and consular premises against any intrusion or damage, and to prevent any disturbance of the peace of these missions or impairment of their dignity, and to prevent any attack on diplomatic agents and consular officers.

"In this context, and expressing their deep concern at these attacks, the members of the Security Council called on all authorities to protect diplomatic and consular property and personnel, and to respect their international obligations in this regard."

In his statement issued on Wednesday, Ki-moon said he was "deeply saddened by yesterday’s attack against the United States Consulate in Benghazi, Libya, resulting in the deaths of four US diplomats, including Ambassador John Christopher Stevens, as well as Libyan employees of the Consulate.  The Secretary-General condemns this attack in the strongest terms.  The Secretary-General extends his condolences to the United States Government and to the bereaved Libyan and American families."
Ki-moon also stated that the UN rejected defamation of religion in all forms.  "At the same time, nothing justifies the brutal violence which occurred in Benghazi yesterday". He reminded the Libyan authorities of their "obligations to protect diplomatic facilities and personnel" and welcomed statements by Libyan authorities that they would bring the perpetrators to justice.
The Secretary-General also reinfoced the UN's commitment to continue working with the government and the people of Libya.