Al-Moussawi, the military spokesman, said security forces repelled an overnight attack on the facility, killing around 20 militants and damaging eight vehicles. The casualty figures could not be independently verified.
The Sunni militant offensive has ramped up the pressure on Iraq's political leaders to quickly form a new government that can confront the insurgents and keep the country from fracturing along ethnic and sectarian lines.
Prime Minister Nouri al-Maliki, a Shiite whose State of Law bloc won the biggest chunk of the vote in April elections, is angling for a third consecutive term, and vowed last week he would not withdraw his candidacy — despite calls for him to step aside.
He has been widely accused of trying to monopolize power. Rivals and former allies alike say he has exacerbated the crisis by failing to pursue reconciliation with the country's Sunni minority, which complains it is treated like second-class citizens by al-Maliki's government.
Late Saturday, Shiite cleric Muqtada al-Sadr said the next prime minister must come from State of Law, but he urged the bloc to put forward a candidate other than al-Maliki, saying an alternative nominee "will help end the suffering."
"It is necessary to demonstrate the national and paternal spirit for a higher and noble goal," al-Sadr said in a statement released by his office. "I mean changing the candidates, which will be a welcome and blessed step during this hard time the country goes through."
The comments marked a shift in al-Sadr's position. He previously said that the next prime minister must be Shiite, but not from State of Law.
The political group that al-Sadr used to head controls 33 out of the 328 seats in parliament. Al-Maliki's bloc holds 92.
Also, Iran's state news agency said an Iranian pilot named Shoja'at Alamdari Mourjani was killed while defending Shiite holy sites in the Iraqi city of Samarra, which is home to one of the most revered shrines in Shiite Islam. It said Mourjani was buried Friday in a village near Shiraz in southern Iran.
It was not clear in what capacity Mourjani was fighting in Iraq, nor how he was killed.
Iran, the regional Shiite power, has said it will provide any help necessary to aid Iraq in its current crisis. Tehran has maintained close ties with successive Shiite-led governments in Iraq since the 2003 ouster of Saddam Hussein, a Sunni who oppressed the Shiites.
Late Sunday, a bomb exploded inside a coffee shop in the primarily Shiite neighborhood of Washash in western Baghdad, killing five people and wounding 17, police officials said. Hospital officials confirmed the casualty figures.
The officials spoke on condition of anonymity because they weren't authorized to brief the media.
Associated Press writer Nasser Karimi contributed from Tehran.