The home affairs ministry has written to the Nobel Peace Prize winner saying her party is breaking the law by maintaining party offices, holding meetings and issuing statements, the New Light of Myanmar newspaper reported.
"If they really want to accept and practise democracy effectively, they are to stop such acts that can harm peace and stability and the rule of law as well as the unity among the people including monks and service personnel," it said.
Suu Kyi was freed in November after seven straight years of house arrest, less than a week after an election in Myanmar that critics said was a charade aimed at preserving military rule behind a civilian facade.
Her National League for Democracy (NLD) party was disbanded by the military rulers last year because it boycotted the poll, saying the rules were unfair.
The New Light said the party could transform into a social organisation provided it obtained permission from the authorities.
The English-language daily, a mouthpiece for the regime, also warned that a planned political tour by Suu Kyi could lead to turmoil.
"We are deeply concerned that if Daw Aung San Suu Kyi makes trips to countryside regions, there may be chaos and riots, as evidenced by previous incidents," a commentary in the newspaper said.
"The government has said that Daw Aung San Suu Kyi is just an ordinary public member, so it will not restrict her from travelling and doing things in accordance with the law, but she shall honour the laws for the rule of law."
No schedule has been announced for the trip. Security is a major concern as her convoy was attacked in 2003 in an ambush apparently organised by a regime frightened by her popularity.
