"Although it was clear that the video call was with Mr Poroshenko, the Foreign Minister became suspicious after the conversation. Other people's contact details were requested. Taking into account his concerns, the Minister stopped responding," the statement said.
It was later stated that the situation was investigated and it was determined that the messages and video call were "hoaxes".
It was emphasised that the incident was made public in case Cameron's video was manipulated and later used, and to make others aware of such a risk.
"While the Foreign Secretary regrets his mistake, he believes it is important to draw attention to this behaviour and to step up efforts to counter the use of misinformation," the statement said.
No details were given about who Cameron met with.
