Assyrians: Iraqi Christians Protest over Killings
At least eight Christians have been killed in the past two weeks in the volatile northern city of Mosul.
The killings prompted an appeal by Pope Benedict on Sunday for Iraqi authorities to protect vulnerable religious minorities.
The UN says more than 680 Christian families have fled Mosul since the recent attacks.
Sunday's protests took place in the town of Hamdaniyah, 35km (22 miles) east of Mosul, and also in the capital, Baghdad.
Marchers in Hamdaniyah, many carrying olive branches, were led by priests including the second-most-senior Chaldean bishop, Shlemon Warduni.
"The government has done nothing so far," he said, calling on the US, UN and EU to "defend the rights of Christians in Mosul".
In Baghdad, a smaller number of protesters carried Iraqi flags and shouted "stop the killing of Christians", at the gathering in Ferdus Square.
The BBC's Hugh Sykes, in Baghdad, says Islamic militants associate Christians with what they regard as "crusaders" - the US-led forces that invaded Iraq in 2003.
The recent killings were only the latest in a list of violent attacks on Christians in Iraq.
In 2004, five Christian churches in Baghdad were bombed.
Christians - and Christian priests - have been kidnapped, murdered, and maimed.
Christian businesses - often sellers of alcohol - have also been bombed and burned.
Two years ago, the Chaldean Catholic Archbishop of Mosul, Paulos Faraj Rahho, was kidnapped and murdered.
Most of Iraq's estimated 700,000 Christians are Chaldeans - Catholics who are autonomous from Rome but recognise the Pope's authority.
In his address on Sunday, the Pope said: "I appeal to the civil authorities to complete every effort to give security again to the population, and in particular, to the most vulnerable religious minorities."
The latest murders come ahead of Iraq's parliamentary election on 7 March.