As the four victims were buried, new Prime Minister Mehdi Jomaa said the state would not be undermined by "terrorism." (Agencies)
"Tunisia is free, terrorism out," and "Faithful to our martyrs" were among slogans chanted by the protesters outside the governor's office in the town in northwestern Tunisia on Monday.
The country has been rocked by sporadic attacks blamed on jihadists since the 2011 revolution that toppled a decades-old dictatorship and touched off Arab Spring uprisings across the region.
The protesters expressed their support for the security forces, stopping outside two police posts, chanting the national anthem and shouting, "We are with you!"
Many later joined the separate funerals of the four victims of Saturday's attack. On that day, a group of armed men who had set up a roadblock in the Jendouba area, some 40 kilometres from the Algerian border, shot dead a civilian and a prison warden as their car approached, the Interior Ministry said.
When a National Guard patrol was sent to investigate, the militants again opened fire, killing two policemen and wounding another two.
The armed group consisted of three Tunisians and two Algerians, according to police. Interior Minister Lotfi Ben Jeddou attended Monday's funeral of one of the officers.
In Tunis later, Jomaa attended a meeting of the national Security Council alongside President Moncef Marzouki and Ben Jeddou.
"I assure you that the morale of the security forces is strong. There is a determination" on their part, he told journalists in remarks broadcast on state television after the meeting.
"These terrorists had a plan to undermine the state. Because they could not do so, now they want to undermine the confidence that has returned in the citizens," he added.
A government of independents led by Jomaa and tasked with steering Tunisia to fresh elections took the oath on January 30, replacing an Islamist-led administration under a hard-won deal to end months of political turmoil.
Much of the deadly violence witnessed in Tunisia since the January 2011 uprising has been blamed on Ansar al-Sharia, a hardline Salafist movement accused of having links to Al-Qaeda.
The government has said Ansar al-Sharia was behind the separate assassinations last year of two secular politicians, killings that plunged Tunisia into political turmoil, but the group never claimed responsibility for those or any other attacks.
As the four victims were buried, new Prime Minister Mehdi Jomaa said the state would not be undermined by "terrorism."