"The country is facing significant security problems," he said, pointing to a string of attacks since last week that have claimed dozens of lives.
But Kobler does "not expect the outbreak of civil war" although he said there is a policy deadlock in the country, according to an interview published in the Berlin daily Tagesspiegel.
The UN envoy said he was neither optimistic nor pessimistic about the future of Iraq after the departure of US forces earlier this month, but said, "I am realistic and take the facts into account."
"Iraq now has security forces and they are in a far better state than some years ago," he added. "There will be no break-up of Iraq."
Just days after the last US troops left on December 18, Iraq was shaken by a number of attacks, against the backdrop of a deepening political crisis between the Shia majority and the Sunni minority.
A suicide attack on Monday killed five people and left dozens wounded at the interior ministry in Baghdad.
Last Thursday a wave of attacks across the capital killed 60 people, and violence in the provinces the same day claimed another seven lives. It was the deadliest day in Iraq since mid-August.