In a post on Twitter, Khalilzad said: “Over the last few days, there has been a clear rise in violence in Afghanistan.
“This escalation is regrettable as Afghans, including many civilians, are losing their lives.
“Given the recent start of Afghanistan Peace Negotiations, it is imperative all sides reduce violence significantly,” he said.
This comes as Afghan negotiators and the Taliban’s talks team discuss intra-Afghan negotiations in Doha.
However, a marked increase in violence has been evident over the past week.
Khalilzad’s comments meanwhile coincide with World Peace Day, which is celebrated each year to honor victims of war and promote non-violence.
The UN General Assembly declared September 21 as a day devoted to strengthening the ideals of peace, through observing 24 hours of non-violence and cease-fire.