"It seems many more people are missing than anyone thought even possible", Trump told reporters from the White House South Lawn shortly before boarding the Marine One helicopter to fly to Joint Base Andrews.
Trump reiterated claims that raking helps, during an interview on Fox News that aired Sunday.
Trump's remarks on Saturday came shortly after he added insult to his handling of the California wildfires by wrongly referring to the name of Paradise, a town ruined by the blazes as "Pleasure", during the same news conference.
Niinisto told Finland's Ilta-Sanomat newspaper that he and Trump had discussed California wildfires during their brief meeting in Paris on November 11. "We're going to have that, and we're going to have forests that are very safe".
"That should have been all raked out, you wouldn't have the fires".
Over a thousand of people are unaccounted for while dozens have been confirmed dead.
Pyry Luminen posted a photo of herself pretending to hoover the forest floor, while Teemu Pasila tweeted that he was busy raking "some 228,000 square kilometres of forest".
In an interview following Mr Trump's comments, Finnish President Sauli Niinistö said he did not recall mentioning raking to the USA leader.
"And yeah, managing that pine litter adjacent to our homes and buildings is super important ... but the reality is, to manage every little bit of fuel with a rake is not practical."
Seemingly placing the blame once more he insensitively said about seeing firefighters clearing dried brush: 'This should have been all raked out'. The wildfire has been called the deadliest and most destructive in the Golden State's history.
Mr Trump is a noted climate change sceptic, and rejects it exacerbates the conditions which lead to fires.
Trump's "compliment" for Finland caused a stir on social media, where hashtags like #RakeAmericaGreat Again and #RakeNews were widely shared.
Meanwhile, Finns used social media to mock Trump's claim.