The U.N. Assistance Mission in Afghanistan said election observers in the country have reported more than two dozen cases of violations since campaigning began.
The Independent Election Commission in Afghanistan opened the campaign season for presidential contenders Feb. 2 and for provincial council challengers March 4. Campaign season ends April 2 and elections are scheduled April 5.
Ban said in his latest report to the Security Council that preparations for this year's election were better than during previous contests. Nevertheless, he said the April election "will not be without flaws."
Past elections were seen as skewed in favor of President Hamid Karzai, who is ineligible to compete because of term limits.
U.N. special envoy to Afghanistan Jan Kubis this week said Afghans needed a secure voting environment. The resurgent Taliban recently issued threats against the election process.
This year's election will mark the first time power is handed peacefully from one democratically elected government to the next.
"If credibly conducted, with a result that is widely accepted, they will provide a mandate for a new leadership to address the country's many challenges in ways that strengthen stability and reinforce national unity," Ban said in his report.