"I want the Tunisian people to understand that we are in a war against terrorism and that these savage minorities do not frighten us," Essebsi said after a visit to the hospital where the wounded were being treated.
Three Tunisians and 18 foreign tourists, including from France, Italy, Japan and Colombia, were killed, the BBC said, citing the Tunisian government's figures.
EU foreign policy chief Federica Mogherini said Wednesday that the European Union would "fully support Tunisia in the fight against terrorism." EU officials blamed the Islamic State (ISIL) for committing the attack.
According to Al Jazeera, the attack was the jihadist militant groups' attempt to destabilize Tunisia that is considered as the only successful example of democratic transition followed 2011 Arab Spring.
The country has been hit by several terrorist attacks in recent years. In 2002, 19 people died in a bomb blast at a synagogue in the resort of Djerba. In February, about 20 al-Qaeda-linked militants attacked a mountain checkpoint in Tunisia and killed four policemen.
According the International Centre for the Study of Radicalisation and Political Violence, somewhere between 1,500 and 3,000 Tunisians are among the estimated 20,000 foreign fighters who have joined militant groups in Iraq and Syria.
