The bombing, which came despite a driving ban aimed at preventing such attacks, occurred about 2 p.m. as worshippers were leaving after religious services in northern Baghdad, police Lt. Mohammed Khayoun said, adding that the bomb was planted near the door of the mosque. Maj. Khalil Ibrahim later said 14 people were killed and five were wounded.
Earlier Friday, five mortar rounds fell near the Shiite Imam al-Hussein mosque in Balad Ruz, 45 miles northeast of Baghdad, killing two people and wounding six, provincial police said.
The strikes against the mosques were the latest in a week of tit-for-tat sectarian attacks, although violence appeared to ebb on Friday, the start of the Islamic weekend.
Authorities also have imposed a weekly four-hour driving ban starting at 11 a.m. to prevent car bombs that have frequently targeted the main Islamic weekly religious services.
Shiite clerics, meanwhile, denounced the Israeli attacks on Lebanon during Friday prayers, while hundreds of Iraqis demonstrated to show solidarity with the Lebanese as fears mounted that violence in the region could spiral out of control.
The Iraqi protests came as Israeli warplanes struck Beirut, while Hezbollah fired more rockets at Israeli towns across the border. Police said three people were killed and 55 wounded in the air strikes, raising the death toll to 60 on the third day of fighting.
In other developments:
"We condemn and denounce the crimes of the Zionist enemy against our Lebanese people," Shiite Sheik Asaad al-Nassiri, an aide to radical cleric Muqtada al-Sadr, said in his sermon at the Kufa mosque. "This offensive is considered an oppressive act against the Lebanese people and is targeting the legitimate resistance that has been an example of bravery."
Several thousand Shiites also took to the streets in the Shiite slum of Sadr City in eastern Baghdad to protest the Israeli military action.
"No, no to Israel, no no to America," demonstrators chanted.
"Let everyone understand that we will not stand idle," read one of the banners carried by the demonstrators. "Iraq and Lebanon are calling, enough silence Arabs," read another.
Hundreds also staged protests in the cities of Kut and Amarah, southeast of Baghdad, denouncing the Israelis.
In other violence reported by police on Friday, gunmen attacked an Iraqi army checkpoint on a highway near Kirkuk, in northern Iraq, killing 11 soldiers and wounding three.
A taxi driver was killed in a drive-by shooting in the volatile Dora neighborhood in southern Baghdad.
Gunmen in southeastern Baghdad also opened fire on a minivan carrying passengers to the Shiite holy city of Karbala, killing five of them, including a woman and a child.
In a similar attack in western Baghdad, gunmen opened fire on a minivan, wounding three passengers.
An unidentified body dressed in traditional Arab clothing was found shot in the chest and showing signs of torture was found in Aziziyah, 35 miles southeast of Baghdad.
A Sunni policeman was shot to death in front of his home in Mosul, while gunmen in a car killed the bodyguard of a judge elsewhere in the northern city, Col. Abdul-Karim al-Jibouri said.