Both Iran and Syria have been hit by sanctions from the United States and Europe, the former over its controversial nuclear programme and the latter due to its bloody attempts to suppress a revolt that began last March.
"We have put in place new procedures since February 1," Mudher Mohammed Saleh, the deputy governor of the Iraqi central bank, told AFP on Saturday.
Banks that buy dollars from the central bank must now provide the identity of whoever placed the order and "prove that they have an account in the bank and the origin of their income," Saleh said.
"We are concerned that some people buy dollars on behalf of others," he said, without elaborating.
Asked if Iranian and Syrian traders were trying to buy dollars, Saleh said: "This increase in demand for dollars, while the region has serious problems, led us to put the new procedures in place."
In 2010, the Iraqi central bank sold about $100 million per day. That increased to between $150 and $160 million in the first 10 months of 2011, and reached around $200 million in the last three months, peaking at $300 million.
Saleh added that transactions had experienced a dramatic fall in the first two days of February, ranging from $3-$4 million.
Saleh said the new measures were not adopted at the request of the United States.
"This is an international issue, and we are implementing international procedures," he said.