It was not immediately known what ended the protest or whether the government granted any concessions to the former soldiers.
The talks took place as UN peacekeepers in armoured vehicles and Haitian police surrounded the former Cap-Hatien prison, which is now used as a music school.
Fred Blaise, a UN police spokesman, said a second soldiers'protest in a former barracks in Ouanaminthe, a northern Haitian town on the border with the Dominican Republic, had ended as well.
Patrick Elie, an adviser to Rene Preval, the Haitian president, said the protest was "political manipulation" to keep pressure on Preval, who already this year has faced protesters trying to storm the national palace and the Senate's removal of his prime minister, who has not been replaced.
"I believe (the protest) is part of this campaign to put pressure on a government that it is at its weakest moment in some years," Elie told the Associated Press news agency.
Senator Youri Latortue, who has been pushing for the creation of a new Haitian army, said he has not given money or assistance to the ex-soldiers and that he did not support their tactics.
But he told the AP that he, and not Preval's administration, was best suited to deal with the soldiers and prevent an escalation of the protests.
"They trust that we in the Parliament, we fight to defend their rights," Latortue said.
The Senate was scheduled to vote on Wednesday on the president's third nominee for prime minister, Michele Pierre-Louis. But the vote was again postponed because only 15 senators attended the vote, one less than needed for a quorum.
Preval held talks on Tuesday with legislators over the inclusion of various political parties in Pierre-Louis' proposed Cabinet in an effort to ensure their approval of her appointment.
The 9,000-strong UN peacekeeping force has provided the country's only real security force since the army was disbanded.