Afghanistan holds provincial council and president elections April 5. It will mark the first time power is handed peacefully from one democratically elected government to the next.
Haysom said following a meeting Tuesday with members of the country's Independent Election Commission a fair vote was an important benchmark for development.
"With so much at stake, Afghans deserve to have elections that are inclusive, credible, transparent and free from any activity which could taint the results," he said in a statement. "This is also crucial for Afghanistan's future stability."
Past elections were seen as skewed in favor of Afghan President Hamid Karzai, who is ineligible to compete because of term limits.
"Fraud amounts to stealing the vote of a fellow Afghan citizen, which is unacceptable," the U.N. deputy envoy said.
Elections coincide with an effort by international forces to transition from a combat to an advisory role. U.S. and NATO officials have said those plans are complicated by Karzai's reluctance to sign the necessary security agreements.
He said he'd leave that to whoever wins the April contest.