State-media New Light of Myanmar says Brigadier General Khin Yi summoned National League for Democracy Chairman U Aung Shwe to police headquarters Thursday to deliver the warning.
On Monday, members of a 10-party opposition coalition, Committee Representing People's Parliament, which is led by the National League for Democracy, met and demanded the release of Aung San Suu Kyi.
The police chief said that the organization was illegal and argued that its demands were unlikely to bring about any good for the nation and the public.
Aung San Suu Kyi has spent most of the past 17 years under detention after the military refused to recognize her party's election victory in 1990.
Burma's military government has pledged to take steps toward democracy, but has been reluctant to follow through on its promises, despite pressure from Western nations and other countries in the region.
Earlier this week, the Burmese government announced that it would continue to detain 80-year-old democracy advocate Tin Oo. Tin Oo is the vice chairman of the National League for Democracy.
Information for this report is provided by AFP