Pruitt called the purported murder of James Foley, the journalist, an international war crime.
"The Associated Press is outraged by the killing of James Foley and condemns the taking of any journalist's life. We believe those who kill journalists or hold them hostage should be brought to justice. Further, we believe the assassination of a journalist in wartime should be considered an international crime of war," Pruitt said in a statement posted on the AP's website.
On Tuesday, the group the Islamic State of Iraq and Syria (ISIS or ISIL) released a gruesome video claiming to show Foley's beheading. In the video, which has since been deleted from YouTube, an unnamed militant threatened to kill more hostages unless President Barack Obama agrees to ISIS demands in the region.
Pruitt said such actions were a fundamental threat to democracy.
"The murder of a journalist with impunity," he said, "is a threat to a free press and democracy around the world."