Trump made the comments during a meeting with a special envoy from South Korea on Wednesday afternoon, Yonhap reported.
Hong Seok-hyun, a former ambassador to the United States, met with Trump for 15 minutes at the Oval Office with Vice President Mike Pence, National Security Advisor H.R. McMaster and senior White House advisor Jared Kushner by Trump's side, according to South Korean television network JTBC.
Hong delivered a letter from South Korean President Moon Jae-in. Trump said he looked forward to working closely with Moon to resolve the North Korea nuclear issue, Hong said.
"We may presently be at the stage of pressure and sanctions, but if conditions are right, [Trump] said he would be willing to take part in making peace," the South Korean special envoy said.
The issue of THAAD deployment on the peninsula was not raised during Hong's discussions with Trump, but the former South Korean diplomat said the U.S. missile defense system was addressed during a separate meeting with Gen. McMaster.
McMaster reportedly told Hong the United States is aware of the controversy over THAAD deployment.
"I said there is a controversy about procedural problems in the course of the deployment, and I talked about the need for this issue to be discussed at the National Assembly," Hong told reporters at the Korean War Veterans Memorial after paying tribute to U.S. soldiers who served during the 1950-53 Korean War.
Hong said the issue of THAAD's cost was not raised during the talks.
In April Trump had said Seoul should pay as much as $1 billion for the missile defense system.