"We captured four security officers related to the last set of bombings," Maliki told a gathering of tribal leaders from mostly Sunni Salahuddin province.
McClatchy Newspapers reported Maliki did not say which ministry employed the four security personnel taken into custody.
At least 68 people died and about 200 were injured in the string of car bombings Thursday in Baghdad that analysts say are further evidence there are forces at work intent on fomenting sectarian violence between the country's majority Shiites, who dominate the Maliki government, and its minority Sunnis.
Maliki has ordered the arrest of Iraqi Vice President Tariq al-Hashemi, alleging he used his security forces to carry out terrorist attacks. Al-Hashemi has moved to the largely autonomous Kurdistan province.
"I'm here as vice president," McClatchy reported al-Hashemi said during an interview with al-Jazeera Saturday evening. "I moved from Baghdad to Suleimaniyah at the invitation by the president [Jalal Talabani, a Kurd]. I am performing my duties as always."
Al-Hashemi said he would return to Baghdad if assured his freedom would be protected.