Parks presidency has been rocked by allegations that a personal friend of hers used her ties to meddle in state affairs and wield improper influence.
Foreign Ministry Spokesman Cho June-hyuck said the decision to miss the summit of the Asia-Pacific Economic Cooperation (APEC) forum was made because of the North Korean nuclear crisis.
"It was already decided in September that the president will not attend this years APEC summit," Cho told a briefing.
North Korea conducted its fifth nuclear test on Sept. 9 in defiance of UN Security Council resolutions, sharply escalating tension on the Korean peninsula already troubled by Pyongyangs missile programme.
Parks absence at the APEC summit in Lima will mark the first time a leader of South Korea, a founding member, has not attended since 1993, the foreign ministry said.
Park has been severely bruised by the scandal involving her friend, Choi Soon-sil, who has been charged with abuse of power.
Park said on Tuesday she will withdraw her nominee for prime minister if parliament recommends a candidate and is willing to let the new premier control the cabinet, seeking to defuse the crisis, Reuters reported.
Parks comments at a meeting with the speaker of parliament indicated she was willing to relinquish some control over state affairs - a key demand by opposition parties.
It was not clear whether the proposal to transfer more power to the premier, who is normally a figurehead, would include the job of representing the country diplomatically.
Parks chief foreign policy adviser said last week that she would attend a summit between China, Japan and South Korea, which is expected to be held this year.