Human Rights Watch has criticized Iraqi authorities for using what the group described as "repressive means" to muzzle peaceful protests.
Last week's demonstrations in Iraq were held to mark the one-year anniversary of nationwide protests against widespread corruption, poor basic services, and high unemployment.
In those 2011 protests, 16 people were killed and more than 130 injured in clashes between police and protesters.
New York-based Human Rights Watch said in a statement that in the buildup to last month's peaceful anniversary demonstrations, activists were threatened with violence and arrest.
It said security forces surrounded the sites where protesters were gathering in Baghdad and in Sulaymaniyah, in the automonous Kurdish region.
In Sulaymaniyah, the group said men in civilian clothes assaulted demonstrators.
Several journalists covering the protests were detained.
With AFP reporting