Afghanistan has filed an official protest with Pakistan, alleging that its forces came under fire early Monday along a contested stretch of the countries' common border.
The Afghan Foreign Ministry issued a strong statement that "any further unprovoked attacks by Pakistani forces, Pakistan will bear responsibility for any consequences."
It is unclear if there were any casualties in the clash, which sparked a large protest in the Afghan capital, Kabul, drawing thousands of men chanting "Death to Pakistan."
The fresh clashes broke out between troops in an area of the border where soldiers from both countries exchanged gunfire last week. Afghan officials said the fight broke out after Pakistani troops returned to the site of a gate on land both sides claim along the porous border.
Last week, crossfire on the border killed one Afghan border guard and wounded two Pakistani security personnel.
Pakistan and Afghanistan have blamed each other for starting the firing late last Wednesday on what is a crucial battleground in the fight against the Taliban militants who operate in both countries. Officials say the artillery exchange lasted several hours and focused on the disputed gate area.
Afghan President Hamid Karzai has called on the Taliban to fight Afghanistan's enemies instead of "destroying their own country." The remarks in Kabul Saturday did not mention Pakistan directly but were widely seen as a swipe against it.
Afghanistan and Pakistan have had tense relations since Pakistan's formation, and Pakistan helped the Taliban take power in Afghanistan in the 1990s.
Afghan officials say Pakistan has a long history of of supporting Afghanistan's Taliban and other insurgent factions. Pakistan has, in turn, accused Afghanistan of giving safe haven to militants on the Afghan side of the border.
Both countries are U.S. allies in the fight against militants.