"I'm not going to talk about specific individuals," Cameron told reporters at an event in Wales.
"When there are people anywhere in the world who commit appalling and heinous crimes against British citizens, we will do everything we can with the police, with the security services, with all that we have at our disposal to find these people and put them out of action."
On Thursday, Emwazi was identified as the masked killer who has fronted Islamic State beheading videos.