Taliban fighters have launched attacks across the country in recent weeks
The Taliban have called on people in Afghanistan to boycott next month's presidential and provincial elections.
In a statement on a Taliban website, the movement ordered fighters to block roads on the eve of the elections and stop voters going to polling stations.
The statement said that participation in the vote would be a show of support for "invading Americans".
Afghanistan has seen a rise in violence ahead of the poll and there are grave concerns about security on the day.
The BBC's Bilal Sarwary in Kabul says this is the most specific threat yet made by the Taliban in the run-up to the elections on 20 August, but it is not an unexpected move.
The Taliban have always maintained they want foreign forces to leave the country and have made general calls for election boycotts before.
"How could Afghans consider this an Afghan process when, contrary to all their national traditions... it is planned by the Americans, financed by the Americans?" the statement says.
The Taliban message goes on to urge fighters to launch attacks against "enemy centres" and "prevent people from attending the elections and one day ahead of elections they must block all roads and highways for government and civilians vehicles".
Mr Fahim (left) is one of Hamid Karzai's two running mates
It said that people should free Afghanistan through resistance and holy war.
In the past week alone there have been two attacks on Afghan election campaigns.
On Tuesday a campaign manager of presidential candidate Abdullah Abdullah was badly hurt after his vehicle was attacked in Laghman province. Two days earlier there was an assassination attempt on Mohammed Qasim Fahim, a running mate of President Hamid Karzai.
Elections are due to take place amid tight security on 20 August when Mr Karzai is hoping to secure a second term.
About 40 other candidates are challenging him for the presidency.
The Taliban statement also comes days after the Afghan government announced it had agreed a truce with Taliban insurgents in the north-western province of Badghis for the elections.
Although Taliban militants later denied any deal, our correspondent says it served to underline the disjointed and complex nature of the insurgency - with many different groups operating under a Taliban banner.
In June the US and the UK launched an offensive in the south of the country where the Taliban insurgency is at its fiercest, in a move aimed at shoring up security for the vote.