A single rocket exploded in an empty field near the town of Sderot in southern Israel, without inflicting casualties or damage.
Israeli Defense Minister Ehud Barak ordered the temporary closure of checkpoints on the border with Gaza through which vital supplies of commercial and humanitarian cargo are brought into the Hamas-controlled territory.
The little-known Palestinian 'Brigades of Akko Martyrs' group took responsibility for the attack.
A spokesman for the group, recently formed from ex-operatives of various Palestinian security bodies which were disbanded after last year's coup in Gaza, told RIA Novosti on Thursday that the group aimed to disrupt the ceasefire with Israel and "bring Palestinians back on the path of armed resistance."
The spokesman said the name of the group was chosen as a sign of solidarity with Arab residents of the northern Israeli town of Akko, which in early October saw fierce clashes between Jewish and Arab residents after an Arab motorist entered a predominantly Jewish area on the Jewish holy day of Yom Kippur.
Israel and Hamas-led militants reached a truce agreement on June 19. Under the six-month deal, Hamas agreed to stop firing rockets into Israel, which in turn agreed to reopen its border crossings with the Gaza Strip to allow supplies of essential goods into the Palestinian territory.
Since then, Gaza militants have occasionally launched rocket attacks on Israeli territory, with Israel closing the border crossings in response.