Two pipelines were attacked on Friday night, a spokesman for the occupation interim oil ministry said on Sunday.
Three anti-tank rockets hit a pipeline south of Baghdad causing a "significant" leakage, Asim Jihad said, adding that an explosive device also hit a pipeline in the Mashada region, 50km north of the capital.
The latest attacks severely affected the output of the country's refineries, already operating at half their capacity, Jihad said.
However, he did not provide further details.
According to Iraqi officials, there have been 86 attacks on Iraq's oil infrastructure since the fall of Saddam Hussein in April, leading to crippling fuel shortages.
The attacks have also hampered the country's efforts to boost production and secure much needed funds for reconstruction.
On Wednesday, the oil ministry imposed further restrictions on gas sales, limiting each motorist to 30 litres a day, compared with a 50-litre limit announced on 10 December.
In parts of Iraq, motorists are being restricted to an even smaller daily ration.
The massive lines at gas stations come despite the fact that Iraq sits on top of the world's second largest oil reserves after Saudi Arabia.