The gas-rich nation's foreign ministry "expressed in strongest terms its condemnation of the killing of US journalist James Foley at the hands of a criminal group," in a statement published by the official QNA news agency.
A video of Foley's beheading was posted online on Tuesday by the IS, a jihadist group operating in Iraq and Syria, prompting global condemnation.
In the nearly five-minute video, the group declares that Foley was condemned to die in retaliation for US President Barack Obama's ordering of air strikes against IS positions in northern Iraq.
Doha's reaction comes a day after Germany's development aid minister, Gerd Mueller, accused Qatar of financing IS jihadists.
"A story like this always has a history," Mueller said in an interview with public broadcaster ZDF. "Who is financing these troops? Hint: Qatar.