"Rusafa is a focal point for us right now," the statement quoted US Brigadier General John Campbell as saying.
"We're addressing that area with increased security forces and patrols."
In western Baghdad, however, one person was killed and three wounded by a car bomb in the Mansur district, an area traditionally home to wealthy Iraqis and foreign embassies, an Iraqi security source said.
The joint Iraqi-US patrols are a key element in the Baghdad security plan designed to restore control of no-go areas to forces controlled by Iraq's unity government.
Up to 50,000 Iraqi security forces and 35,000 US troops are to eventually take part in what many consider a last-ditch operation to save Iraq from plunging into a full-scale civil war.
The plan aims to use a major influx of forces to occupy and retain districts by implanting joint combat posts where Iraqi troops and US soldiers are to be based around the clock.
According to the United Nations, around 17,000 people died last year from the sectarian violence in Baghdad, which has a population of six million people.