Both.   Back in 1938 Orson Welles convinced many people  into thinking we were under attack by Martians. That was not his intent. It was a radio show. It was entertainment. Was it lying because some actually believed we were under attack?  And were some of the listeners who called friends and relatives to warn them of the "attack",  lying? No, they believed it to be true. They were passing on "truth" as it appeared to them at the moment. But it wasn't true and they weren't lying. Both are true statements.  President Trump and our media sometimes report or talk about "facts" they believe to be true at the time, but may have either not done enough research or there is insufficient verification of known facts in a given story or speech..  
 A lie is very different. It is when you absolutely "know" something is false yet repeat it,  or report it anyway.  For instance, if I knew the Martian invasion was just a radio show but told people it was an actual invasion. That is a lie. Make sense?