Trump's tweet came a day after Newsom and Govs. Jay Inslee and Kate Brown of Washington and Oregon, respectively, sent a letter to the president asking him to double federal funding for forest management.
Newsom noted that California has pledged $1 billion over the next five years to ramp up its efforts, which include clearing dead trees that can serve as fuel.
More than half of California's forests are managed by the federal government, and the letter noted the U.S. Forest Service's budget has steadily decreased since 2016.
"Our significant state-level efforts will not be as effective without a similar commitment to increased wildland management by you, our federal partners," the letter read.
In a Tuesday event on wildfire safety, Newsom had praised Trump for always providing California with necessary disaster relief funds.
In November, the deadliest and most destructive U.S. wildfire in a century leveled the California town of Paradise, killing 86 people and destroying more than 14,000 homes. Trump toured the fire devastation with then-Lt. Gov. Newsom and then-Gov. Jerry Brown on Nov. 17.
Other California Democratic lawmakers condemned Trump's tweet.
House Speaker Nancy Pelosi responded, saying "Trump's threat insults the memory of scores of Americans who perished in wildfires last year & thousands more who lost their homes."