"The coalition to defeat ISIS has retaken almost 100 percent of the territory once held by these killers in Iraq and Syria," President Trump said in a speech at the World Economic Forum in Davos, Switzerland.
"There is still more fighting and work to be done and to consolidate our gains."
ISIS has been dealt a string of defeats across Iraq and Syria in recent months.
The US-led coalition said on Tuesday it had killed as many as 150 ISIS fighters in an operation in the middle Euphrates River Valley in Syria, where some remained entrenched.
Kurdish ground forces have played a critical role in defeating ISIS.
On Wednesday ISIS claimed responsibility for a deadly attack on Save the Children's office in east Afghanistan that left at least two people dead and 14 others wounded.
"We are committed to ensuring that Afghanistan never again becomes a safe haven for terrorists who want to commit mass murder to our civilian populations," President Trump added in his speech.