President Donald Trump says he is unfairly being blamed for the New Zealand mosque massacre.

Trump tweeted Monday that the media "is working overtime to blame me for the horrible attack in New Zealand." He adds: "They will have to work very hard to prove that one."

The gunman in last week's massacre left a document in which he called himself a white nationalist and referred to Trump as "a symbol of renewed white identity."

Trump had expressed sympathy for the victims, but played down the threat of white nationalism across the world, saying he didn't consider it a rising threat despite data suggesting it's growing.

In the past, Trump has drawn criticism for saying "both sides" were to blame for violence at a deadly white supremacist demonstration.