According to BBC news "3000 people did not die in the two hurricanes that hit Puerto Rico," Mr. Trump wrote on Twitter, without offering evidence for the claim.
He added that Democrats had inflated the official death toll to "make me look as bad as possible".
The official figure was released last month after an independent study.
On Thursday, Mr. Trump wrote in a pair of tweets that Democrats were attacking him "when I was successfully raising Billions of Dollars to help rebuild Puerto Rico".