Lebanese forces this week deployed to the border as fighting from Syria's civil war neared the border. The Syrian government last week warned Lebanon it would respond with force to border militancy.
Kobler told the U.N. Security Council that Iraq hosted around 120,000 Syrian nationals. Another 80,000 Iraqis fled the conflict and are included in the estimated 1.2 million internally displaced.
He said he was concerned the strains could push the conflict across the border. More than 40 Syrian soldiers and 10 Iraqis were killed in Iraq in early March.
"Iraqis face a complex set of interrelated problems, among them, the very real potential for a spill-over of violence from Syria," Kobler said.
The United Nations estimates that at least 70,000 people have died and more than 1 million have been displaced by Syrian fighting that began March 2011.
U.S. Sens. Carl Levin, D-Mich., and John McCain, R-Ariz., top members of the Senate Armed Services Committee, called on President Barack Obama to consider air and missile strikes to end the Syrian conflict.
"We believe there are credible options at your disposal, including limited military options, that would require neither putting U.S. troops on the ground nor acting unilaterally," the senators wrote.
NATO has Patriot missiles deployed in Turkey for defensive purposes.