Ban and the Council, in separate statements, said there was no justification whatsoever for targeting diplomatic personnel and civilians.
“The Secretary-General is appalled by this senseless act of terror,” according to a statement issued by Ban’s spokesperson, Mr Stephane Dujarric.
The UN chief also expressed his deepest condolences to the family of Amb. Karlov and to the Government and people of the Russia.
Ban said he was “following the unfolding situation closely” and wished those who were reportedly injured in the attack a speedy and full recovery.
In a separate statement, the Security Council, while condemning the deadly terrorist attack, expressed its deep condolences to the family of the ambassador and the Russian Government.
The Council reiterated the need to bring the perpetrators, organisers, financiers and sponsors of terrorist attacks to justice.
Council members reaffirmed that terrorism in all forms constitutes one of the most serious threats to international peace and security, and that any acts of terrorism are criminal and unjustifiable.
The 15-member Council also stressed the fundamental principle of the inviolability of diplomatic agents and consular officers and the obligations.
These include, under the 1961 Vienna Convention on Diplomatic Relations and the 1963 Vienna Convention on Consular Relations, to take all appropriate steps to prevent any attack on diplomatic agents and consular officers.