Iraqi security forces were on high alert for several hours until Sunday morning following clashes between the Syrian army and rebel forces near the border, officers said.
From 11:00 pm (2000 GMT) on Saturday until Sunday morning, Iraqi forces were on their highest level of alert in the area surrounding the village of Albu Kamal, on the Iraq-Syria border.
"Our forces stepped up security after clashes broke out and explosions were heard on the Syrian side of the border," border guards Captain Ali Juwair said.
"The warning means we have to be on full alert, and we have to stay in our positions unless advised to do otherwise."
Juwair said the clashes were between Syrian government troops and the rebel Free Syrian Army at several checkpoints in Albu Kamal.
He said later that the alert level was lowered on Sunday morning, but did not specify a time.
An Iraqi army liaison officer charged with handling communications between the border guards and the army said that the clashes broke out at around 11:00 pm on Saturday, at which point Iraq's forces were put on alert.
"We received a call from an Iraqi army division deployed near the border, informing us of the clashes on the Syrian side, and it was requested that soldiers take precautions and not get involved unless there was a crossing of the border," he said, speaking on condition of anonymity.
Syrian President Bashar al-Assad's regime launched a brutal crackdown on opponents from March last year that has left thousands dead, and clashes regularly take place between rebels and Syrian government forces.
The head of a UN mission has warned of "civil war" in Syria after his observers counted more than 92 bodies, 32 of them children, in the central town of Houla following reports of a massacre there.