A booby-trapped car exploded near a restaurant in Baghdad's northern district of Kadhmiyah, killing at least six people and wounding 15 others, the source said on condition of anonymity.
In a separate incident, a car bomb detonated at the busy intersection of al-Faris al-Arabi Square in western Baghdad, killing two people and wounding five others, the source said.
Also in the morning, another car bomb exploded near Kahramanah Square in Baghdad's central district of Karrada, killing a civilian and wounding 11 others, while a fourth car bomb, in the same district, killed one and wounded six others, he said.
In a separate incident in the city center, gunmen launched an attack on a police checkpoint in Sarafiyah, killing six people and wounding three others, the source added.
In Baghdad's southwestern district of Saidiyah, two people were killed and nine wounded when insurgents blew up two roadside bombs and opened fire on Iraqi police with silenced weapons, he said.
Elsewhere, two roadside bombs exploded in quick succession in Baghdad's southern district of Abu Dsheer, killing two people and wounding 10 others, the source added.
Outside Baghdad, five people were wounded when two roadside bombs were detonated in Taji area, some 20 km north of the city, he said.
Iraqi cities have been plagued by waves of deadly attacks including suicide bombings since the U.S. troops pulled out of the country.