The travel advice, which was issued before US jets struck jihadist positions near the city of Arbil, does not extend to the Kurdish capital itself, an spokeswoman said.
In an updated guidance, the Foreign Office advised against all travel to those areas of the Kurdistan region affected by fighting following attacks by jihadist militants this week.
"If you're currently in these areas you should leave now," it said.
The Foreign Office also advised against all travel to Anbar, Nineveh, Salah Al-Din and Diyala provinces and all of the area south of Kirkuk City limits.
For the rest of Iraq, London advises against all but essential travel.