The brief statement on the presidency's Facebook page said the decision was taken following consultations with the speaker of parliament and the prime minister, and would take effect Monday.
Just over a month ago, Tunisia was stunned by a bloody attack by a single gunman on a beach resort killing 38 tourists, mostly Britons. The attack followed another one on tourists back in March.
Tunisia had been criticised for lax security at tourist sites, and Britain called for all its citizens to depart in the wake of the attack.
Under the state of emergency, the army has been deployed to guard sites and authorised to shoot to kill if under threat. Rallies of more than three people are also banned - though this provision has rarely been enforced.
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In the past week, Tunisian security forces have carried out an aggressive string of raids on suspected militants in cities around the country, arresting dozens and killing at least one.
Tunisia's parliament nearly unanimously passed a new anti- terror law on July 25 that is meant to aid the fight against militant groups. But it has provoked fears that the freedoms won in the 2011 revolution might be threatened.
"Tunisia's new counterterrorism law imperils human rights and lacks the necessary safeguards against abuse," said the statement. "The law grants security forces broad and vague monitoring and surveillance powers.