Trump said he had planned to meet with Afghanistan's president, also a secret meeting with the Taliban's major leaders on September 8.
US President Donald Trump on Saturday said he cancelled peace talks with Afghanistan's Taliban leaders after the insurgent group said it was behind an attack in Kabul that killed an American soldier and 11 other people.
Trump said he had planned a secret meeting with the Taliban's "major leaders" on Sunday at a presidential compound in Camp David, Maryland. Trump said he also planned to meet with Afghanistan's president.
But Trump said he immediately called the talks off when the insurgents said they were behind the attack.
"If they cannot agree to a ceasefire during these very important peace talks, and would even kill 12 innocent people, then they probably don't have the power to negotiate a meaningful agreement anyway," Trump said on Twitter.
Taliban fighters, who now control more territory than at any time since 2001, launched fresh assaults on the northern cities of Kunduz and Pul-e Khumri over the past week and carried out two major suicide bombings in the capital Kabul.
One of the blasts, a suicide attack in Kabul on Thursday, took the life of US Army Sergeant 1st Class Elis A. Barreto Ortiz, 34, from Puerto Rico, bringing the number of American troops killed in Afghanistan this year to 16.
A spike in attacks by Taliban insurgents in Afghanistan has been "particularly unhelpful" to peace efforts there, a senior US military commander said on Saturday as he visited neighbouring Pakistan, where many Taliban militants are based.
US Marine General Kenneth McKenzie, who oversees American troops in the region, declined to comment on the diplomatic negotiations themselves.
Earlier this week, US and Taliban negotiators struck a draft peace deal which could lead to a drawdown in US troops from America's longest war. But a wave of Taliban violence has cast a long shadow over the deal.
"It is particularly unhelpful at this moment in Afghanistan's history for the Taliban to ramp up violence," McKenzie, head of US Central Command, told reporters travelling with him.
McKenzie said for the peace process to move forward, "all parties should be committed to an eventual political settlement" which, in turn, should result in reduced violence.
"If we can't get that going in, then it is difficult to see the parties are going to be able to carry out the terms of the agreement, whatever they might or might not be," McKenzie said.
Under the draft accord, thousands of US troops would be withdrawn over the coming months in exchange for guarantees Afghanistan would not be used as a base for militant attacks on the United States and its allies.
However, a full peace agreement to end more than 18 years of war would depend on subsequent "intra Afghan" talks. The Taliban have rejected calls for a ceasefire and instead stepped up operations across the country.
New Civil War?
For Afghans, the Taliban's recent escalation of attacks has underscored fears it may be impossible to reach a stable settlement following any complete US withdrawal.
Many have worried about a fracture along ethnic and regional lines, with Persian-speaking Tajiks and Hazaras from the north and west against southern and eastern Pashtuns, the group that have supplied most of Afghanistan's rulers and where the Taliban draw most support. Memories of the 1990s civil war are vivid.
Some Taliban are based in neighbouring Pakistan, where McKenzie held talks on Saturday with a top Pakistani general. More talks are scheduled for Sunday.
McKenzie said he did not know whether any of the planning for the recent wave of attacks in Afghanistan came from Pakistan-based militants.
But McKenzie commended Pakistan for supporting the peace efforts in Afghanistan, in the latest sign of an improvement in long-fraught relations between Washington and Islamabad.
"A lot of Pakistanis have been killed by militant attacks inside Pakistan. I think Pakistan sees the benefits of a stable Afghanistan," McKenzie said.