The IS-linked Aamaq news agency said Thursday that the person who carried out the "attack in front of the British parliament in London was a soldier of the Islamic State."
It added that the person "carried out the operation in response to calls for targeting citizens of the coalition."
IS has called on its supporters to carry out attacks against citizens of the U.S.-led coalition that has been targeting the group since 2014.
IS, who have been responsible for numerous bloody attacks around the globe, have also previously claimed certain attacks in a show of opportunism. Britain's government has not identified the suspect.