The gunfire came during a third day of disturbances following a loyalist rally at City Hall where protesters voiced their opposition to restrictions on flying the union flag, The Guardian reported.
A spokesman for the Police Service of Northern Ireland said two men were arrested on charges related to the shooting, including a 38-year-old man accused of attempted murder, the British newspaper said.
Eleven others were arrested in conjunction with the unrest, The Guardian said.
Police used water cannons once again Saturday to disperse about 100 rioting loyalists after riot squad officers were pelted with bricks, bottles, fireworks and smoke canisters. A total of at least 40 officers have been injured in confrontations with protesters since new flag-flying rules were invoked.
Saturday's violence allegedly began when republican youths hurled items which loyalist demonstrators claimed struck a baby.
The violence is a "disgrace," Northern Ireland First Minister Peter Robinson said Friday as police clashed with about 300 protesters, the Belfast Telegraph reported. The protesters sent bricks, fireworks and Molotov cocktails flying at police who responded with water cannons, police said.
"The violence and destruction visited on the PSNI is a disgrace, criminally wrong and cannot be justified," Robinson said. "Those responsible are doing a grave disservice to the cause they claim to espouse and are playing into the hands of those dissident groups who would seek to exploit every opportunity to further their terror aims."
The unrest began in early December when the Belfast City Council voted to limit the flying of the flag at city hall to 17 days a year, special occasions such as the official celebration of the queen's birthday. Previously, the British flag flew over the building every day.
Robinson said the protesters, like dissident republicans who have attacked or even killed police officers, want to undermine the coalition government and are seeking a return to direct rule from London. Robinson, who heads the Democratic Unionist Party, said all "right-thinking unionists" will use political means to achieve their goals.