According to the Russian Foreign Ministry, he stated this at a meeting in New York with UN Secretary General Antonio Guterres. 

“Lavrov also particularly emphasized the imperative of strict adherence by all employees of the UN Secretariat to the principles of impartiality and equidistance in strict accordance with the Charter of the Organization,” the statement said.

Earlier it was reported that Lavrov was holding a meeting with the UN Secretary General.

Later it became known that Lavrov and Guterres discussed cooperation between Russia and the UN in New York.