"Billions of dollars are sent to the State of California for Forrest fires that, with proper Forrest (sic) Management, would never happen", Trump said in a tweet.
He later re-sent the message after correcting the spelling of "forest".
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.
The latest announcement drew an immediate response from the state's new governor.
"Disasters and recovery are no time for politics", wrote Newsom, who on Tuesday announced an interstate partnership and a pair of executive orders to combat the wildfire problem. "The people of CA ― folks in Paradise ― should not be victims to partisan bickering".
Wildfire survivors in Butte, Los Angeles and Ventura counties had been eligible for federal funds.
"Our climate is changing - we have to change with it".
More than one-half of the 33 million acres of forest in California are managed by federal government agencies, according to the University of California's Division of Agriculture and Natural Resources. Another 40 percent is held by companies, Native American tribes or families. In an automated email reply, the agency said, "Due to the federal funding hiatus, we are not able to respond to general press queries".
Fortune reached out to FEMA for comment Wednesday. "It's absolutely shocking for President Trump to suggest he would deny disaster assistance to communities destroyed by wildfire", Senator Dianne Feinstein said in a statement. Trump contended Monday that water could be used for "fires, farming and everything else".
House Speaker Nancy Pelosi (D-Calif.) called on House Minority Leader Kevin McCarthy (R-Calif.) to join her in condemning the president's comments, saying that President Trump's "threat insults the memory of scores of Americans who perished in wildfires a year ago and thousands more who lost their homes".
In this file photo taken on November 10, 2018 Flames from the Camp fire burn near a home atop a ridge near Big Bend, California.