Attacks killed at least eight Shiite pilgrims in Baghdad province on Tuesday, while security forces killed six militants, Iraqi officials said.
A suicide bomber detonated explosives among pilgrims walking south of Baghdad, killing four, while militants in a car threw a hand grenade at pilgrims in the capital, killing at least four others.
The two attacks also wounded at least 27 more people.
The violence came after two car bombs targeted Shiite pilgrims south of the Iraqi capital on Monday night, killing at least 24 people and wounding over 50.
Hundreds of thousands of people, many of them on foot, make pilgrimages to the holy city of Karbala during the 40 days after the annual commemoration marking the death of the Prophet Mohammed's grandson, Imam Hussein.
The 40th day, known as Arbaeen, falls on December 23 this year.
Sunni militants including those linked to Al-Qaida frequently target members of Iraq's Shiite majority, whom they consider to be apostates.
Also on Tuesday, Iraqi soldiers killed a suicide bomber south of Baghdad, while five more militants died in clashes with security forces, the spokesman for the security command responsible for Baghdad said in emailed statements.
Violence in Iraq has reached a level this year not seen since 2008, when the country was just emerging from a period of brutal sectarian killings, raising fears the country is falling back into all-out conflict.
More people died in violence in the first eight days of this month than in the whole of last December, and over 6,500 people have been killed since the beginning of 2013, according to AFP figures based on security and medical sources