The palace has come under repeated fire from gangs that have paralysed the capital Port-au-Prince. A nine-member presidential transition council is to be sworn in at the palace, and although no date has been announced, rumours circulated that it could happen this week.
The council is expected to name an interim prime minister and help set up a government that will eventually organise elections in the Caribbean island nation.
"Whether or not you're installed, this message is for you: Brace yourselves," gang leader Jimmy "Barbeque" Cherizier ominously warned in a Tuesday video shared on social media.
Cherizier has called for toppling the government.
The US military on Tuesday said it bolstered defences at its embassy.
Outgoing Prime Minister Ariel Henry has for more than a year called for international troops to help police fight the gangs. But plans moved slowly and were eventually paused when he announced in March his plan to step down, pending a new interim government.
Since then, attacks have escalated and the transition has lagged.
The presidential council "has to put in place a minimum of security so that the population can go about its business," he said.
Gangs are accused of perpetrating widespread rape, ransom kidnappings and indiscriminate killings. The conflict has seen hundreds of thousands of people internally displaced and millions pushed into acute hunger while key ports remain closed.
