Donald Trump criticised the American broadcaster during a live press conference with Theresa May.
The US President claimed CNN was “fake news” as he refused to answer a question from one of their reporters.
Mr Trump pointed at Fox News reporter John Roberts to ask a question when a CNN journalist asked if he could quiz the American leader.
The US President said: “No, no, CNN is fake news, I don’t take questions from CNN.”
He repeated: “CNN is fake news, I don’t take questions from CNN. John Roberts of Fox, let’s go to a real network.”
The CNN reporter was heard quickly replying: “We are a real network too, sir.”
During the press conference, the US President also claimed the relationship between the UK and the United States was the “highest level of special”.
“I give our relationship, in terms of grade, the highest level of special.
“We start off with special. I would give our relationship with the UK.
“And now, especially after these two days with your Prime Minister, I would say the highest level of special.
“Now am I allowed to go higher than that? I am not sure. But, it is the highest level of special.
“They are very special people, it is a very special country.
“As I said, I have a relationship because my mother was born in Scotland, so very important to me.”
During the joint press conference with the US President on Friday, Mrs May said: “We have got a lot to discuss. We are going to be discussing the special relationship, which is great, between the UK and US.
“We are going to be discussing the real opportunities we have got to have this trade deal coming up when we leave the European Union.
“And of course we will discuss foreign policy and defence and security issues, where we work really closely together with the US.”
The US President will meet the Queen at Windsor Castle at 3:30pm, where he will be treated to a Guard of Honour when he arrives at the royal residence and joins the monarch for afternoon tea.