The six incidents appear to be aimed at avenging the deaths of Shiites captured and killed by the Islamic State group.
The Kurds also find themselves fighting the Sunni militants across the northern front. On Friday, a suicide bomber blew himself up at a peshmerga checkpoint outside Kirkuk, killing 28 people and wounding 30, said Kirkuk police chief Maj. Gen. Torhan Abdul-Rahman Youssef. The explosion set several vehicles in the vicinity on fire.
Hospital officials confirmed the casualty figures. They spoke on condition of anonymity because they weren't authorized to brief the media.
In recent days, the political divisions between Baghdad and the Kurds have grown increasingly bitter. On Wednesday, al-Maliki accused the Kurds of harboring Sunni militants.
The Kurds responded by declaring their politicians will boycott Cabinet meetings, renewing demands that al-Maliki step down.
Baghdad, in turn, suspended all cargo flights to the Kurdish region's two main airports. And on Friday, al-Maliki appointed temporary replacements for all five Kurdish ministers in his Cabinet, said Deputy Prime Minister Hussain al-Shahristani.
Al-Shahristani said he himself was appointed acting foreign minister to stand in for Hoshyar Zebari, who was one of the most prominent Kurds in the government and has been Iraq's top diplomat for more than a decade.
The dispute comes as al-Maliki is struggling to fend off an attempt to remove him from his post by political factions — including the Kurds but also from former Shiite allies who blame him for the failures to confront the Sunni militant offensive and have long accused him of monopolizing power.
In Baghdad, national lawmakers are struggling broker an agreement on a new government and leadership, including the posts of prime minister, president and speaker of parliament, after April elections.
The legislature is scheduled to meet Sunday for its second session amid calls for the quick formation of a new government that can confront the militants and hold the country together. Al-Maliki, whose State of Law bloc won the most seats in the elections, has shrugged off calls to step aside.
The United States and other world powers, as well as Iraq's top Shiite cleric, have pressed for a more inclusive government that Iraqis of all stripes can rally around.
On Friday, Ayatollah Ali al-Sistani again urged lawmakers to move swiftly toward a compromise, calling on them to "rise above selfish aims."
"The challenges ... threaten civil peace and the unity of the social fabric and forecast a divided and disputed future for Iraq," Abdul-Mahdi al-Karbalaie, a cleric who represents the reclusive al-Sistani, told worshippers in a sermon Friday in the holy city of Karbala.
Associated Press writers Qassim Abdul-Zahra and Ryan Lucas in Baghdad, and Maamoun Youssef and Mariam Rizk in Cairo contributed to this report.