Special envoy Stephen Biegun said that any new weapons tests or provocations by the North would be "most unhelpful" with negotiations stalled.
North Korea has accused the secretary of state of "talking nonsense" and "fabricating stories."
Amid fears of yet another missile test, the secretive state released footage of an orchestrated mass mourning.
There are few details about the latest missile test, but North Korea has often used foreign-trained scientists and foreign-sourced materials.
The regime is about to celebrate its 69th year of existence as the Democratic People's Republic of Korea, and the South is on high alert for a possible missile test.
After its most recent test, the country's leadership is likely confident enough to enter into negotiations with the West.
America is headed toward a nuclear crisis with North Korea and Trump needs real diplomacy, not Twitter, say experts.
As Trump and Netanyahu prepare for their Feb. 15 meeting, focus has shifted to Iran's ballistic missile test last week.
The United States is expected to impose sanctions on multiple Iranian entities as early as Friday following Tehran's recent ballistic missile test.
Sanctions monitors said Tehran had violated a U.N. Security Council resolution by test-firing a missile.
A missile test announced by Iran over the weekend was an apparent violation of a U.N. Security Council resolution.