In his message posted on Facebook and Twitter, Moon also vowed to make every effort to support people's wishes to lead happy lives this year. The Lunar New Year's day falls on Friday.
"South and North Korean athletes in PyeongChang are exchanging greetings in our friendly language. This is the scene of the national holiday that we have been looking forward to for too long," the president said.
"I express my deep gratitude to the citizens who have cheered for South and North Korean athletes' heroic efforts," he added.
Pyongyang has sent 22 athletes to compete in five disciplines, including 12 women's ice hockey players who are part of the single team with their South Korean counterparts. The quadrennial games run until Feb. 25.
Moon also wished citizens happiness in the New Year.
"When families are happy, the country can become happy," he said. "The government will make every effort to prop up your endeavors to become happy." (Yonhap)