Demonstrations broke out on Saturday morning after the Southeast Asian country went into its second nationwide internet shutdown since the military seized power and arrested civilian leaders on Monday.
According to photographs posted by the news portal Mizzima, police officers in bulletproof vests with riot shields blocked the main roads, while crowds marched flashing a three-finger salute, which has become a symbol of the fight for democracy and was used by Thai and Hong Kong protesters.
Demonstrators were also wearing red, the colour of the National League for Democracy, whose government was overthrown by the military.
The portal added that hundreds of people were detained during the protests, while the news website Frontier reported that the demonstrations were peaceful and police officers were inactive.
Myanmar's military overthrew the government on Monday and declared a year-long state of emergency after accusing State Counsellor Aung San Suu Kyi's party of fraud over its recent election victory.