Palestinian security officials reported no injuries.
Israel went to war against militants in Hamas-ruled Gaza last winter to quash eight years of rocket and mortar fire that terrorized southern Israel and killed 18 civilians.
More than 1,400 Palestinians were killed in the war, and since it ended on Jan. 18, the attacks have decreased sharply. According to the military's count, 270 rockets and mortars have been fired at Israel since the three-week offensive ended on Jan. 18, compared with more than 3,300 in 2008.
But Israel says weapons and weapons-making components still reach militants through tunnels under Gaza's border with Egypt. And sporadic fire continues, including a rocket attack Wednesday that caused no injuries.
The Israeli military said in a statement that it would "respond to any attempt to disrupt the calm in Israel's southern communities."