Israel temporarily closed its border crossings with the Gaza Strip on Wednesday after militants from the Hamas-controlled territory fired a rocket into southern Israel.
"After a rocket was fired into Israel from the Gaza Strip on Tuesday, Defence Minister Ehud Barak instructed the Gaza crossings to be closed starting on Wednesday morning," a defence ministry official said.
The official did not say how long the crossings would remain shut.
Gaza militants fired the rocket on Tuesday, the first in more than six weeks, causing no damage or injuries, Israeli police said.
Israel and Hamas agreed to a ceasefire in June. It called for a cessation of cross-border violence and a gradual easing of Israel's blockade on the Gaza Strip, which was tightened after the Islamist group seized control of the territory in 2007.
The truce has largely held, although Gaza militants occasionally fire rockets into Israel, which responds by temporarily closing its borders with the coastal territory.