Iran agreed to renew discussions with the permanent members of the U.N. Security Council - the United States, Russia, China, Britain and France - plus Germany last month, more than a year after previous talks failed.
Iraq said last Wednesday it had offered to host the nuclear negotiations following a request from neighbouring Iran.
A statement on Iraq's Foreign Ministry website said all parties had agreed to hold the next meeting in Baghdad.
"The group of 5+1, the European Union and the Islamic Republic of Iran recently reached a settlement which includes holding the next meeting on international nuclear negotiations with Iran in Istanbul on April 14, provided that the following meeting will be in Baghdad, with all sides in agreement," the statement said.
Iraq's Shi'ite-led government shares close ties with Iran, which is jostling for more influence in the region against Sunni Arab Gulf powers.
Iran has been cut off from global financial services and embargoes have been imposed on its main export, oil, after Washington and Brussels imposed the toughest ever sanctions when previous nuclear talks collapsed.
The United States and its European allies suspect Iran of covertly developing atomic weapons, accusations Tehran denies. The Islamic state says it has a sovereign right to nuclear activities, which it says are entirely civilian.
It accuses the nuclear-armed West of hypocrisy and of trying to stifle its technological progress.
Israel has not ruled out a military strike against Iran if diplomacy fails.