“There is a severe travel warning for Tunisia [high concrete threat],” the Counter-Terrorism Bureau said in a statement released by the office of Prime Minister Benjamin Netanyahu.
“Terrorist elements, especially those affiliated with Global Jihad, continue to operate in Tunisia and commit attacks; therefore, there is a high threat level against Jewish targets,” said the statement.
“It is recommended that visits to Tunisia be avoided,” it added.
Last year Tunisia was hit by a string of attacks claimed by the Islamic State group that killed dozens of holidaymakers in the North African country.
But the 2014 edition of Lag BaOmer in the Tunisian holiday island of Djerba took place without incident, despite a similar warning from Israel.
This year the festival – during which pilgrims the tombs of revered rabbis as well as the famed El Ghriba synagogue – will take place May 25-26.
Djerba is home to one of the last Jewish communities in the Arab world.
But the number of pilgrims visiting El Ghriba have fallen sharply since a 2002 suicide bombing claimed by Al-Qaeda that killed 21 people.
Prior to the attack, the celebrations in Djerba would attract almost 8 000 people each year, including from France, Israel, Italy and Britain.