The air campaign by global and government forces accounted for 6 percent of civilian casualties in 2017, with 295 people killed and 336 wounded, a 7 percent increase over the previous year.
That compares to a total 11,434 casualties in 2016, when there were 3,510 deaths and 7,924 wounded.
But the decline in total deaths was tempered by the report's finding that the number of airstrikes conducted by global military forces and Afghan air forces increased significantly - and with it the number of airstrike-related deaths.
Meanwhile, spokesman for Afghan Defense Ministry, Dawlat Waziri, said that the security forces would do their best to protect civilians during military operations against militants in Afghanistan.
"In 2017, UNAMA documented 631 civilian casualties (295 deaths and 336 wounded) from airstrikes, a seven percent increase from previous year, and the highest number recorded by UNAMA (since 2009)", Bell warned.
Insurgents account for 65 per cent of the overall casualty figures, with 42 per cent attributed to Taliban militants and ten per cent to Daesh, the United Nations report says.
"While we did see an improvement on the battlefield by Taliban and pro-government forces, more still needs to be done".
Over two thirds of those killed and wounded were attributed to anti-government fighters belonging to groups such as the Taliban and the Islamic State militant group (ISIS).
The largest attack in front of the German embassy in Kabul killed 92 people and injured another 491 people, according to the report.
Pro-government forces caused a fifth of the civilian casualties according to the report, with 16 percent attributed to the Afghan national security forces, two per cent to worldwide military forces, one per cent each to pro-government armed groups and undetermined pro-government forces.
The Taliban caused 42 percent of the total casualties, ISIS 10 percent and other anti-government factions who were unidentified 13 percent.
The UN also points out that airstrikes by global and Afghan forces caused more casualties than the previous year.
The use of improvised explosive devices (IEDs) - suicide and non-suicide - by armed groups led to the majority of the casualties past year, with ground engagements accounting for the second-highest number of victims. UNAMA documented that, in 2017, 359 women were killed - a rise of five per cent - and 865 injured.
Women and children continued to bear the brunt of the armed conflict.
"We are concerned that we will see greater harm this year unless necessary steps are taken by all parties to prevent civilian casualties", cautioned Tadamichi. But the figures highlighted the high number of casualties caused by militant bombs, the United Nations said.
In line with the overall reduction in civilian casualties in 2017, child casualties decreased by 10 per cent, compared to 2016.
The report stresses the importance of implementing Protocol V, noting that in 2017, UNAMA documented 164 deaths and 475 injured as a result of explosive remnants of war.