Kim Yo-jong, a powerful adviser and sister of North Korea’s leader, on Wednesday dismissed President Trump’s abrupt decision to scale back major military exercises with South Korea, saying the attempted overture “holds no interest for us.”

Ms. Kim, a spokeswoman for her brother Kim Jong-un’s government, said in a statement carried by state media that the reduced exercises were still “provocative and aggressive.”

She also said she was “unaware” of any communication between the governments in Pyongyang and Washington, contradicting President Trump’s claim on Tuesday that Mr. Kim had responded to his outreach.

Ms. Kim’s repudiation came amid Mr. Trump’s attempts to spur new talks with the North’s leader. On Wednesday, Mr. Trump said he expected to meet with Mr. Kim later this year.

Ms. Kim’s comments came one day after the Pentagon said it would end planned drills with South Korea one week earlier than scheduled. On Sunday, Mr. Trump ordered the Defense Department to reduce the 11-day training exercise, called Ulchi Freedom Shield.

U.S. allies in the region view the annual drills, a fixture of the decades-old security alliance between the United States and South Korea, as crucial to military preparedness and deterrence amid China’s expanding territorial ambitions and North Korea’s military posturing.

Under Mr. Kim, the North has not let up its nuclear weapons program. It has issued threats about its nuclear capabilities and conducted regular missile launch tests.

On Wednesday, the country’s state media channel, the Korean Central News Agency, carried an official statement denouncing the United States and South Korea as “warmongers” responsible for worsening tensions in the region through military exercises that it claimed had become increasingly aggressive each year.

North and South Korea are still technically at war, though the fighting paused after a 1953 armistice established the Demilitarized Zone between the two countries. Since then, the United States and South Korea have remained close military partners, though the relationship has been strained during Mr. Trump’s first and second terms.

Hanging over the tensions with South Korea is Mr. Trump’s inability to extract the United States from the war with Iran, now into its sixth month. His decision to reduce the military drills with South Korea was viewed as a way to punish that country for declining to join the war against Tehran.

Mr. Trump has appeared eager to move on from the conflict in the Middle East and pivot to dealing with Mr. Kim. At least twice in recent months, the American president posted a picture of himself with the North Korean leader on social media.

At summits during Mr. Trump’s first term, Mr. Kim had indulged Mr. Trump’s desire for leader-to-leader talks, but did not make any concessions on his country’s nuclear arsenal.

Mr. Trump’s overtures toward North Korea are not entirely unwelcome by his South Korean counterpart, President Lee Jae​ Myung, analysts said. A staunch proponent of inter-Korean reconciliation, Mr. Lee has urged Mr. Trump to ease tensions in the Korean Peninsula through direct talks with Mr. Kim. ​

North Korea has long cited the joint military drills as a major stumbling block to such efforts, calling them “a rehearsal for an aggressive war.”