At least 92 civilians were killed and almost 500 others injured in a single attack in the capital, Kabul, on May 31.
“The continued use of indiscriminate, disproportionate and illegal improvised explosive devices is particularly appalling and must immediately stop”, he added in a statement.
UNAMA put the civilian death toll at 92, saying it was the deadliest incident to hit the country since 2001.
Casualties among women rose by 23 per cent, while child casualties increased by one per cent.
The U.N. Assistance Mission in Afghanistan documented 1,662 civilian deaths between January 1 and June 30, an increase of 2 percent over the same period previous year.
The UN has condemned an increase in civilian deaths in Afghanistan in the first half of 2017, with 1,662 killed and more than 3,500 injured.
The majority of the victims were killed by anti-government forces – including the resurgent Taliban and in attacks claimed by the Islamic State, the report said, underscoring spiralling insecurity in the country almost 16 years after the USA invasion.
“Each one of these casualty figures reflects a broken family, unimaginable trauma and suffering, and the brutal violation of people’s human rights”, UN High Commissioner for Human Rights, Zeid Al-Hussein said.
“Many Afghan civilians are suffering psychological trauma, having lost family and friends, and are living in fear knowing the risks they face as they go about their daily lives”.
UNAMA annual reports indicate that civilian casualties were on the rise from the withdrawal of many worldwide troops from Afghanistan after 2011 and the official end of NATO’s combat mission in 2014. Meanwhile, 436 children were killed and 1,141 others injured, marking a 9 percent increase in child deaths.
The report commended Afghanistan’s security forces, saying fewer civilians were caught in the crossfire compared to a year ago.
Pro-government forces were responsible for 327 civilian deaths and 618 injuries, a 21 per cent decrease compared with the same period a year ago, although UNAMA noted a 43 per cent rise in civilian casualties during aerial operations (95 deaths and 137 injuries).
The insurgents have expanded their footprint in Afghanistan since USA and North Atlantic Treaty Organisation forces formally concluded their combat mission at the end of 2014, and the Taliban now control a number of districts across the country.
The highest numbers of casualties occurred in provinces of Kabul, Helmand, Kandahar, Nangarhar, Uruzgan, Faryab, Herat, Laghman, Kunduz, and Farah. Attacks by anti-government groups in which improvised explosives were used, were responsible for at least 40 percent of all civilian casualties.
The UN reports include only incidents that have been confirmed after a thorough verification process.