Iraqi President Jalal Talabani has told Pope Benedict XVI that the new Iraq constitution will respect Christians and people who follow other beliefs.
Jalal Talabani and the Pope discussed religious freedom
The Vatican had expressed concern that a legal system based on Islamic law might not guarantee the rights of religious minorities.
The Pope met Mr Talabani amid high security at the Vatican during the president's week-long visit to Italy.
Italy has a 3,000-strong contingent in Iraq, the largest after the US and UK.
Mr Talabani has already met Italian Prime Minister Silvio Berlusconi, who has been under public pressure to withdraw troops.
But the talks in the Vatican focused on the constitution and reconstruction in Iraq.
A Vatican spokesman said the Pope had "underlined the importance of religious freedom".
"I explained to his holiness that the Iraqi constitution will consider all Iraqis, Christians included, equal and will respect all religions," Mr Talabani said, according to AP. "All kinds of freedoms will be guaranteed for all."
There are around 800,000 Christians in Iraq - about 3% of the population. Most Iraqis are Muslims.