The sanctions were emplaced in 2010, following the sinking of a South Korean corvette in the Yellow Sea, in what the South insists was a Northern torpedo attack.
Trump said "eventually we're going to have lots of meetings on USA soil and on their soil by the way".
The summit in Pyongyang was called to restart negotiations between the USA and the North.
Kang Kyung-wha told lawmakers on Wednesday that the government is reviewing whether to lift sanctions South Korea imposed on the North in 2010 following a deadly attack on a warship that killed 45 South Korean sailors.
In a rare sign of discord between Seoul and Washington, Kang said on Wednesday that U.S. Secretary of State Mike Pompeo had expressed "discontent" with an inter-Korean military pact reached during a summit last month.
China, Russia and North Korea believe it is necessary to consider adjusting United Nations sanctions against Pyongyang at an appropriate time, China's foreign ministry said on Wednesday.
Michael’s effect on the DC area: Rain Thursday, wind Friday
It said Michael was now a Category 3 storm with winds abating but still extremely risky at 125 miles per hour (205 kph). The storm, the most severe to hit the Florida Panhandle in a century, brought flash floods, inundating roads and homes.
Asked about Seoul considering lifting some sanctions to create space for diplomacy with North Korea, Trump says: "They won't do that without our approval".
"I'd love to remove them, but we have to get something for doing it", Trump said. The source added Pompeo "used strong language" in the phone call with Kang.
The Trump administration maintains it's made good progress on getting North Korea to denuclearize despite no verifiable actions towards this taking place.
"Noting the important steps taken by the DPRK in the direction of denuclearization, the parties considered it necessary to start a timely review by the UN Security Council of the sanctions measures against the DPRK", the Joint Information Communiqué on Tripartite Consultations said.
The statement contradicts the "maximum pressure" strategy pursued by Washington and enthusiastically endorsed by Tokyo, but which Seoul now appears to be wavering on: It calls for sanctions to remain in place until denuclearization is complete.
Pompeo has since made another trip to Pyongyang, this past Sunday, for a summit that was called to restart negotiations between the USA and the North. Washington has not yet reacted to that suggestion and remains mum on Pyongyang's repeated demands for a peace treaty to end the Korean War and for upgraded bilateral relations.
While some in the United States administration have indicated that denuclearization could be completed within the lifespan of the Trump administration, some experts say it could take more than a decade - assuming it is faithfully implemented, which many doubt.
The denuclearization process, which looked so promising when Kim and Trump met in Singapore in June, is now looking stillborn.