Han made the remarks during a meeting with Harris in Tokyo before they attended the state funeral of late Japanese Prime Minister Shinzo Abe, reports Yonhap News Agency.
Han said the planned visit by Harris to the DMZ on Thursday was a "symbolic" move for the South Korea-US alliance.
Harris's visit to the DMZ comes less than two months after US House Speaker Nancy Pelosi went there.
It also comes after North Korea launched a short-range ballistic missile on Sunday, in an apparent show of force against joint military drills between Seoul and Washington.
Harris said the allies had "a lot of work" to do to strengthen their relations, including their investment in innovation, technology and space.
According to the Prime Minister's office, Han and Harris discussed the global comprehensive strategic alliance, which was agreed by South Korean President Yoon Suk-yeol and his US counterpart Joe Biden in May.
Harris said Washington would seek ways to address South Korea's concerns over a law the US recently passed to tackle inflation, the Yonhap news agency said on Tuesday, according to Reuters.
Harris, who is visiting Japan, met South Korea's Prime Minister Han Duck-soo on Tuesday.
South Korean President Yoon Suk-yeol asked US President Joe Biden earlier this month to help address Seoul's concerns that new US rules on electric vehicle subsidies in the Inflation Reduction Act would hurt the country's automakers.
Harris is expected to join world leaders in Tokyo on Tuesday to commemorate the life of Shinzo Abe, Japan's longest-serving prime minister, who was assassinated in July.
The state funeral will be the first in Japan in 55 years and only the second in the postwar era, The Washington Post reports.