Choe Son Hui, the first vice foreign minister, issued the warning via state media days after Trump spoke of possible military action toward the North and revived his "rocket man" nickname for North Korean ruler Kim Jong Un.
The comments came as prospects dim for a resumption of nuclear diplomacy between the two countries. In recent months, North Korea has hinted at lifting its moratorium on nuclear and long-range missile tests if the Trump administration fails to make substantial concessions in nuclear diplomacy before the end of the year.
Choe said Trump's remarks "prompted the waves of hatred of our people against the U.S." because they showed "no courtesy when referring to the supreme leadership of dignity" of North Korea.
She said North Korea will respond with its own harsh language if Trump again uses similar phrases and shows that he is intentionally provoking North Korea.
"If any language and expressions stoking the atmosphere of confrontation are used once again on purpose at a crucial moment as now, that must really be diagnosed as the relapse of the dotage of a dotard," Choe said.
On Wednesday, the North's military chief, Pak Jong Chon, also warned that the use of force against the North would cause a "horrible" consequence for the Americans. He said North Korea will take unspecified "prompt corresponding actions at any level" if the U.S. takes any military action.
During a visit to London, Trump on Tuesday said his relationship with Kim was "really good" but also called for him to follow up on a commitment to denuclearize. Trump added, "We have the most powerful military we ever had, and we are by far the most powerful country in the world and hopefully we don't have to use it. But if we do, we will use it."
Trump also said Kim "likes sending rockets up, doesn't he?" He added that "That's why I call him rocket man."
In 2017, Trump and Kim traded threats of destruction as North Korea carried out a slew of high-profile weapons tests aimed at acquiring an ability to launch nuclear strikes on the U.S. mainland. Trump said he would rain "fire and fury" on North Korea and derided Kim as "little rocket man," while Kim questioned Trump's sanity and said he would "tame the mentally deranged U.S. dotard with fire."
The two leaders have avoided such words and developed better relations after North Korea entered nuclear negotiations with the U.S. last year. Trump even said he and Kim "fell in love."
Kim and Trump have met three times, starting with a summit in Singapore in June last year. But their nuclear diplomacy has remained largely deadlocked since their second meeting in Vietnam in February ended without any deal due to disputes over U.S.-led sanctions on North Korea.