The violence killed 1,282 and injured 2,176 for a tally of 3,458 civilian casualties, the UN Assistance Mission in Afghanistan (UNAMA) said in a report.
"The reality remains that Afghanistan continues to be one of the deadliest conflicts in the world for civilians," it said in the mid-year report, according to Reuters.
Despite a drop of 13 percent in casualties from the corresponding period last year, UNAMA said the Taliban continued to cause the majority of civilian casualties, mainly through use of explosive devices, abductions and summary executions.
The Taliban were responsible for 43 percent of all civilian casualties and government forces caused 23 percent, chiefly from air strikes and indirect fire during operations, it added.
The UNAMA attributed the 13 percent drop to fewer operations by international forces, as well as fewer attacks by Daesh terrorists.
In February, the United States and the Taliban signed an agreement in Doha, laying out plans for the withdrawal of foreign forces from Afghanistan in exchange for security guarantees from the group.
However, fighting has spiked in recent weeks, prompted by differences over an exchange of prisoners between the Taliban and Afghan government, as Kabul proved reluctant to free hundreds of jailed militants.
The Doha deal provided for the government to release 5,000 Taliban prisoners in exchange for hundreds of Afghan troops, the main plank in starting peace negotiations between the two sides in the effort to end the 18-year-old war.
While the Afghan government has released more than 4,000 Taliban prisoners, it has refused to release another 600, saying they were involved in murder, illicit drug trafficking and major attacks.