A man and four women climbed over the compound's fence in Hanoi at around 3:30 p.m., said Desra Percaya, adding that embassy staff were struggling to find out exactly what they were seeking.
"They don't speak English or Vietnamese," he said.
Officials at the embassy in Hanoi were not available to comment. Five Vietnamese police stood guard outside the embassy shortly after the North Koreans arrived.
Thousands of North Koreans flee their communist homeland to escape hunger and harsh political oppression, many taking a long and risky land journey through China to Thailand, Vietnam, Cambodia and other Southeast Asian countries on their way to eventual asylum in South Korea.
More than 10,000 North Koreans have defected to the South, with most arriving in recent years, since the Korean War ended in 1953.
Last month, four North Koreans sought asylum at the Danish Embassy in Hanoi.