Car bombs killed six people and wounded 30 in and around Baghdad on Sunday, an Iraqi interior ministry official said.
The attacks came after a spate of violence across Iraq last week killed 116 people, breaking a relative calm that had settled after the formation of a new government a month ago.
One car bomb on Sunday targetted a police patrol in Al-Alam neighbourhood of southwest Baghdad killing two people, including one policemen, and wounding eight other people, among them four police, the official said.
Another vehicle packed with explosives was detonated on Abu Nawas street, on the banks of the Tigris river which snakes through the capital, leaving one person dead and six people wounded.
And in the mostly Shiite north Baghdad neighbourhood of Kadhimiyah, a car bomb struck a bus carrying Iranian pilgrims, according to the interior ministry official. One of the pilgrims was killed and eight were wounded in the 10:00 am (0700 GMT) blast.
The pilgrims were in Iraq for Arbaeen commemoration ceremonies, which mark 40 days since the anniversary of the death of Imam Hussein, a cleric who is revered by Shiite Muslims.
In a separate car bomb attack, four people were wounded, including a policeman, in the commercial Karrada district in the centre of Baghdad.
And on a main road in the town of Taji, 25 kilometres (15 miles) north of the capital, a bomb-filled vehicle was blown up, killing two people and wounding four.
Violence has dropped dramatically across Iraq since its peak in 2006 and 2007 but attacks remain common.
A series of blasts, which included suicide bombs, last week killed 116 people and wounded scores more over a three-day period. They targeted security force members and Shiite pilgrims ahead of major commemoration ceremonies and struck in the cities of Tikrit, Baquba, Baghdad and Karbala.
A total of 151 people were killed throughout December.
The apparent spike in violence comes just a month after Prime Minister Nuri al-Maliki formed a new government, ending a protracted political stalemate which followed elections in March.
He has yet to appoint ministers charged with the interior, defence or national security portfolios, however, and currently holds interim responsibility for the entire Iraqi security apparatus.