"I think many of the people that are knocking down these statues don't even have any idea what the statue is, what it means, who it is," Trump said. "Now they're looking at Jesus Christ. They're looking at George Washington. They're looking at Abraham Lincoln. Thomas Jefferson. Not gonna happen. Not gonna happen, not as long as I'm here."
Trump said he would sign an executive order "before the end of the week" to make it easier to prosecute those who attempt to topple monuments, an idea he teased in a tweet earlier this week.
"We're gonna have a very, very, very powerful statement," Trump said during a Rose Garden news conference, adding the FBI is already investigating those vandalizing statues nationwide.
"We've arrested numerous people, as you know, for what took place outside of Washington. In addition, the FBI is investigating hundreds of people throughout the country for what they've done to monuments, statues and even buildings," he added.
After protesters tried to take down a statue of President Andrew Jackson in Lafayette Park across from the White House Monday night, Army Secretary Ryan McCarthy activated a portion of the D.C. National Guard to protect federal monuments.
Not long before Trump spoke, House Republican Leader Kevin McCarthy tweeted he'd just talked to Interior Secretary David Bernhardt, who he said assured him President Trump "will not allow the Emancipation Memorial of President Lincoln to be destroyed by the left-wing mob."
Trump went on to say his administration is going to "consolidate various things" for the executive order and referenced to "very strong laws already on the books."
The Veterans Memorial Preservation Act, for one, already states a person who willfully injures or destroys memorials "commemorating the service of any person or persons in the armed forces of the United States" -- or attempts to do so -- may be imprisoned for up to 10 years.
"That's a long time to have fun one night," Trump said.
But legal questions persist for statues and memorials to leaders who did not fight for the United States, such as Christopher Columbus and Francis Scott Key.
Trump's announcement comes as some protesters in Washington said they will try to remove the "Emancipation Statue" -- depicting President Abraham Lincoln with a freed slave kneeling beside him -- from the city's Lincoln Park on Thursday night.
Del. Eleanor Holmes Norton, D-D.C., said Tuesday that she is introducing a bill in the House of Representatives to remove both statues.
ABC News' Ben Gittleson and Luiz Martinez contributed to this report.