Haitian opposition groups say they will continue months of street protests to try to force his resignation.
The political deadlock is centred on a dispute over a new electoral law, which opposition lawmakers have refused to approve.
On Sunday, President Martelly said he had reached a last-minute deal with the opposition to hold the elections.
But key left-wing opposition party Fanmi Lavalas, which has been at the forefront of anti-government protests, was not part of the deal.
“Martelly will not be able to hold onto power. He is not going to be able to remain. We’re not going to stop until he leaves,” said Andre Michel, a lawyer and opposition figure. via BBC News