Herve Ladsous notes in particular the deaths of 14 peacekeepers in the bloody Darfur region of Sudan. He calls that "totally unacceptable."
Ladsous gave his end-of-year briefing to reporters yesterday.
He also repeated that his department is preparing for the possibility of contributing to the "stabilisation in Syria" if UN Secretary-General Ban Ki-moon requests it.
That will depend on the outcome of Geneva peace talks in January. The talks aim to end the fighting that activists say has killed over 120,000 people in three years.