"It is a disgraceful situation in lives & money!", the tweet says.
In November, the deadliest US wildfire in a century leveled the California town of Paradise, killing 86 people and destroying about 14,000 homes.
During an August cabinet meeting, Trump and other officials downplayed the role of climate change on wildfires, while discussing the abundance of fallen trees creating a natural accelerant.
Trump has repeatedly blamed California officials for failing to manage the state's forests, but numerous areas affected by fire are not forests at all.
"He's already inviting illegal immigrants to his sanctuary state - everybody!" one said of Newsom.
The House Republican minority leader Rep. Kevin McCarthy also is from California. He has said he'll hold back federal dollars for fire disasters before, but has not executed on that threat. "Disasters and recovery are no time for politics", Newsom said in a tweet Wednesday.
The White House did not respond to a request for comment on what specific actions Trump has taken, how they were legally justified and what if anything would be done to help people who are depending on FEMA for food or shelter in the wake of the wildfires.
Wildfire survivors in Butte, Los Angeles and Ventura counties had been eligible for federal funds.
North State Congressman Doug LaMalfa issued a statement in response to President Trump's tweet regarding California FEMA funding. It is considered the deadliest and most destructive wildfire in the state's history.
California faced its deadliest wildfire season this past year, with the Camp Fire and the Woolsey Fire destroying thousands of homes and burning through hundreds of thousands of acres. The president claims that the state is not properly managing their land, unlike Finland, where they rake the forest floor-at least according to Trump.
House Speaker Nancy Pelosi, who represents a district in California, condemned Mr. Trump's tweet Wednesday, calling it a "threat insults the memory of scores of Americans who perished in wildfires past year & thousands more who lost their homes".