This action is in violation of Security Council resolutions and a threat to peace and security in the region," said Guterres.
The UN chief called on North Korea "to ensure full compliance with its international obligations".
North Korea on Sunday carried out its latest test of a ballistic missile, which Pyongyang said was capable of carrying a "heavy nuclear warhead".
Under UN resolutions, North Korea is barred from developing nuclear and missile technology.
Ramp up pressure
The UN Security Council was weighing its response to the latest launch, with diplomats saying that the United States was pushing for a toughly-worded statement of condemnation.
A closed-door emergency Council session was set for Tuesday. The council adopted two sanctions resolutions last year to ramp up pressure on Pyongyang and deny leader Kim Jong-Un the hard currency needed to fund his military programmes.
In all, six sets of sanctions have been imposed on North Korea since it first tested an atomic device in 2006.