"It is now incumbent upon the Taliban to come forward with an offer of their own, and start direct talks with the government to put an end to the suffering of the Afghan people," he said.
"Making peace and reaching out to opponents requires resolve, courage and above all national unity," he added. "Political leaders need to place the national interest above partisan agenda."
He said he hoped that parliamentary elections could be held in 2018 and a presidential vote in 2019.
He also expressed concern about the growing number of civilian casualties at the hands of the Islamic State group in Khorasan province.
The United Nations Assistance Mission in Afghanistan (UNAMA) was launched in March 2002 to help Afghans build a more stable and peaceful society, although 16 years later the country is still racked by violence and instability.
In return, Ghani said the militants should officially recognize the Afghan government and constitution, a perennial sticking point in past attempts to open talks.