"There were a few cases in Iran about three weeks ago, it's under control," WHO cholera coordinator Claire-Lise Chaignat told AFP.
"Iran reacted very well, they dealt with the cases rapidly," Chaignat said, underlining that there was no spread from less than ten known cases.
The cholera cases were first recorded in Iran's western province of Kordestan, next to Iraq, on September 19, she added. The WHO was not aware of any other cases elsewhere in Iran.
Iraq has been grappling with a growing outbreak of cholera, with 3,300 cases and 14 deaths since August, largely in the northeast of the country.
Chaignat said the infection was probably carried into Iran by travellers from Iraq.
"There's a link, that's for sure," she added.
On Wednesday, the WHO called on Iraq's neighbours to reinforce surveillance for cholera, without mentioning the cases found in Iran last month.
Chaignat said Iranian health authorities' swift reaction underlined the value of surveillance instead of travel restrictions to and from affected areas.
The Iraqi outbreak and its spread in the conflict-ridden country has been blamed on poor quality water supplies and a lack of sanitation.