"An individual with ties to the Iranian-aligned militia group Kataib Hezballah believed to be involved in the kidnapping has been taken into custody by Iraqi authorities," Dylan Johnson, the assistant secretary of state for global public affairs, wrote on X.
Iraq said that authorities intercepted a vehicle that overturned as they tried to flee.
"Security forces were able to arrest one of the suspects and seize one of the vehicles used in the crime," the Iraqi interior ministry said in a statement.
"The Ministry affirms that efforts are ongoing to track down the remaining individuals involved, secure the release of the kidnapped journalist," it added.
An Iraqi security source told AFP the abduction occurred in Baghdad. Iraqi authorities did not identify the perpetrator or the victim.
The journalist was identified as Shelly Kittleson, a freelancer, by media advocacy groups as well as Al-Monitor, one of the news outlets for which she worked.
Al-Monitor in a statement said it was "deeply alarmed" by Kittleson's kidnapping and called for her "safe and immediate release".
"We stand by her vital reporting from the region and call for her swift return to continue her important work," the news organisation said.
Kittleson is a "legitimate journalist" with experience in the Middle East and is based in Rome, according to the International Women's Media Foundation.
Baghdad was previously notorious for kidnappings and attempted abductions, but they decreased as the security situation in the country improved in recent years.
Israeli-Russian academic Elizabeth Tsurkov was kidnapped in Baghdad in 2023. She was held for two years until her release last year.
The United States has warned Americans of rising risks in Iraq, where Iran has sway over several Shia armed groups, after the United States and Israel attacked Iran on February 28.
Johnson said that the State Department had "fulfilled our duty" to warn the journalist about threats and reiterated a warning for Americans to leave Iraq.
"The State Department strongly advise all Americans, including members of the press, to adhere to all travel advisories," he said.
