Zalmay Khalilzad said that "there is no final agreement until everything is agreed".
US and Taliban negotiators wrapped up their longest round of peace talks on Tuesday with progress made but no agreement on when foreign troops might withdraw, officials from both sides said.
"Just finished a marathon round of talks with the Taliban in #Doha".
"The conditions for peace have improved".
"Both sides discussed matters pertaining to bilateral relations, regional situation and efforts for peace in Afghanistan", said a foreign ministry statement.
He said a responsible withdrawal of troops would be in the better interest of Pakistan as well as the regional countries.
"When the agreement in draft about a withdrawal timeline and effective counterterrorism measures is finalized, the Taliban and other #Afghans, including the government, will begin intra-Afghan negotiations on a political settlement and comprehensive ceasefire", Khalilzad said.
"My next step is discussions in Washington and consultations with other partners".
Another Taliban source said on condition of anonymity there was frustration on some issues during the peace talks and that a senior member of the Islamist group told USA officials at one point that the Taliban are "not their servants" and need no US approval for any future decisions.
"For now, both sides will deliberate over the achieved progress, share it with their respective leaderships and prepare for the upcoming meeting".
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He said the present government is taking steps to implement the consensus National Action Plan on terrorism in letter and spirit.
"We appreciate how hard it is to end 18 years of war".
Almost 3,500 foreign troops including 2,300 Americans have died in Afghanistan.
The sources have not have provided information regarding draft deal which was concluded between the US and Taliban representatives during the fifth round of talks in Qatar today.
The ongoing peace process in Afghanistan also came under discussion during the meeting of the two foriegn ministers.
Meanwhile, on the ground in Afghanistan, the violence continues.
Washington is seeking assurances that the Taliban will not allow Afghanistan to be used by militants to carry out terrorist attacks overseas - the reason United States forces invaded the country following the September 11, 2001 terror attacks.
Analysts have warned that the Taliban are likely to ramp up attacks in the coming months as they seek to maintain momentum on the battlefield and leverage at the negotiating table.
It was unclear when the next round of talks would be held.