Thailand's military tightened its grip on power as it moved to quell growing protests, saying anyone violating its orders would be tried in military court.
It also took its first steps to revitalise a battered economy, saying nearly a million farmers owned money under the previous government's failed rice-subsidy scheme would be paid within a month.
The military overthrew the government on Thursday after months of debilitating and at times violent confrontation between the populist government of Prime Minister Yingluck Shinawatra and the royalist establishment.
Critics say the coup will not end the conflict between the rival power networks: the Bangkok-based elite dominated by the military, old money families and the bureaucracy, and an upstart clique led by Ms Yingluck's brother and former telecommunication mogul Thaksin Shinawatra.
The Shinawatras draw much of their influence from the provinces.
The military has detained numerous people including Ms Yingluck and many of her ministers, party officials and supporters.
Leaders of six months of anti-government protests against Ms Yingluck have also been held.
The military said they will be freed within a week.
The military has thrown out the constitution, censored the media and dismissed the upper house Senate, Thailand's last functioning legislature.
Today it said anyone accused of insulting the monarchy or violating its orders would face military court.
Power now lies in the hands of army chief General Prayuth Chan-ocha and his junta known as the National Council for Peace and Order, and their priorities appeared to be stamping out dissent and tending to the economy.
An army spokesman warned against protests and told the media to be careful in its reporting too.
"For those who use social media to provoke, please stop because it's not good for anyone," deputy army spokesman Winthai Suvaree said in a televised statement.
Despite the warnings, a small crowd of protesters, some holding handwritten signs such as "Anti the Coup" and "Get out Dictators", formed outside a central shopping centre in the morning and grew through the day.
Hundreds of soldiers, most with riot shields, lined up to contain the crowd and there was some shouting and pushing and at least two people were detained, a Reuters reporter said.
By late afternoon about 1,000 people had gathered at the Victory Monument, a central city hub. A Reuters witness said trucks mounted with water cannon were on stand-by.
In his first public comments since the coup, Mr Thaksin said on his Twitter feed he was saddened by what had happened and he called on the army to treat everyone fairly. Mr Thaksin has lived in self-exile since a 2008 graft conviction and was himself ousted by the military in 2006.