Afghans head to the polls in 23 days. Kubis said the right to vote is especially important given that this election will mark the first time the reins of power are handed from democratically elected government to the next peacefully.
"Like all citizens of the world, Afghan men and women have a basic human right to freely choose their government and leaders without threat or intimidation," he said in a statement Wednesday.
Al-Jazeera and other media outlets reported Monday the Taliban threatened to disrupt the April 5th contest.
There are more than 2,700 candidates cleared to run for seats in provincial councils and 11 candidates competing to replace Hamid Karzai, who's ineligible to seek a third term as president.
Past elections were seen as skewed in Karzai's favor.
April elections come as international combat operations draw to a close in Afghanistan. NATO and U.S. military planners have expressed frustration with charting a future course without a security agreement from the Afghan government.
Karzai said he'd leave the agreement to whoever takes his place after the election.