The official said that if Pakistani and Afghan forces applied pressure on their respective sides of the border at the same time, militants could be caught in the middle.
The official warned that violence was likely to increase as Afghanistan heads toward its September 18 parliamentary elections, but said it was important for Afghans to stay on course for the vote.
The official said it is believed that Taliban and Al-Qaeda elements were "very demoralized" after last year's Afghan presidential elections.
Violence Increasing In South, East
Karzai Says Bin Laden Not In Afghanistana>