When campaigning began on Saturday, President Hamid Karzai ruled out any power-sharing deal to avoid another ballot.
The same day, the Taliban issued their warning, denouncing the contest between Karzai and former Foreign Minister Abdullah Abdullah as "a failed, American process."
Taliban fighters killed dozens of people during the August balloting, firing rockets at several provincial cities.
They also cut off voters' ink-stained fingers that indicated they had cast ballots.