Tunisia's president has ordered emergency laws that temporarily gives the government more powers to strengthen the army and police.
Following an Islamic attack on a beach hotel in Sousse where 38 foreign tourists, including 30 Britons were killed, the state of emergency gives security forces more powers and limits the right to public assembly.
A statement from the president's office said Essebsi will give a speech on national TV at 4pm GMT, when he will address the nation, according to Reuters.
Security has already been strengthened since the attack on 26 June, with armed forces at beaches and hotels.
Criticism was levelled at security forces for not responding more promptly to the scene of carnage at the Imperial Marhaba Hotel, where shots were fired at tourists.
Tunisia's government has promised new laws to increase police powers and provide harsher penalties for terrorism convictions, according to AP.
Immediately after the attack, the prime minister pledged to post armed guards at tourist sites and close mosques outside government control.
Investigators probing the attack have now arrested the girlfriend of gunman Seifeddine Rezgui.
As part of the investigation, security services held the as yet unnamed university student, questioning whether she may have helped plan the massacre, according to the Mirror.
However, Rezgui's girlfriend has denied having any knowledge of the terror plot.
Islamic State (Isis) claimed responsibility for the massacre, which was the most deadly in Tunisia's recent history.
In March, two gunmen killed 22 people at the Bardo museum in Tunis, Tunisia's capital.
Tunisian officials stated that all three gunmen in the two attacks were trained at the same time at jihadist camps in Libya.
Tunisia last had a state of emergency during the 2011 uprising against autocrat Zine el-Abidine Ben Ali.
The final five bodies of the Britons killed in the Tunisian beach attack have been repatriated to the UK on Saturday 4 July. The bodies arrived on an RAF C-17 aircraft at RAF Brize Norton in Oxfordshire at 3pm BST.
Their coffins will be loaded on to hearses and travel to West London Coroner's Court in Fulham. Post-mortems will be carried out before inquests into their deaths.