Shia rebels have started withdrawing from positions they seized near the capital, Sanaa, after a truce with tribesmen allied with the influential Sunni Al Islah party.
Some Houthi fighters, however, refused to give up positions they won after months of deadly battles, despite an ultimatum to leave.
President Abdrabuh Mansur Hadi and Yemen's main parties agreed last month to transform the unrest-riven country into a six-region federation as part of a political transition.
The rebels believe the agreement will divide Yemen into rich and poor regions and have been trying to enlarge their zone of influence to areas closer to Sanaa.
As they advanced they seized areas in the northern province of Omran, leaving more than 150 people dead and overrunning the home base of the Al Ahmar clan which heads the powerful Hashid tribal confederation.
They then advanced to areas located only 15km from the capital. Military sources said their objective was to lay siege to Sanaa.
The army and tribesmen joined forces to stop the rebels and last week the rebels signed a truce with the tribesmen.
On Monday, the head of the presidential commission overseeing the withdrawal of the fighters, Ali Ghashmi reported that soldiers had been deployed in Hamdan province to prevent rebels from returning.
However, a local official told AFP that some fighters were refusing to leave and that the process was being complicated due to "political interference".
'Friday of Dignity'
Hundreds of protesters took to the streets of Sanaa commemorating the third anniversary of one of the bloodiest days of Yemen's 2011 uprising in which at least 50 people were killed in Change Square.
The 'Friday of Dignity' protesters marched in a mock funeral procession from Change Square. Protest banners and chants demanded the "prosecution of the murderers" and the removal of the Attorney General from office.
''We're out today to demand the removal of the Attorney General, and the exposure of the criminals, the ones who committed this massacre, the biggest in Yemen's modern history,'' said protester Hanaa Saleh.
"Three years waiting for justice, and there has been no justice'' demanded the mother of one of the dead, Sala Alshurmani.
Amnesty International has called for the creation of an internationally assisted, independent commission of inquiry to investigate the incident.
An initial investigation set up by the then Attorney General under the regime of former President Ali Abdullah Saleh was dropped two weeks later. The Sanaa criminal court subsequently ordered the new Attorney General to investigate top officials, but has been refused.