Israel says it will hold Hamas directly responsible for any rockets fired into the Jewish state from the Hamas-controlled Gaza Strip, regardless of which militant group launches the strikes.
An Israeli government spokesman, Mark Regev, issued the warning after a rocket landed near the Israeli city of Ashkelon Tuesday. There were no reports of casualties.
A militant group called the Popular Front for the Liberation of Palestine has claimed responsibility for the strike.
The rocket launch follows days of quiet as an unofficial truce has taken hold in Gaza. Palestinian militants have stopped almost all of their rocket attacks against Israel.
But, during a brief visit to Ashkelon shortly before Tuesday's attack, Israeli Prime Minister Ehud Olmert cautioned that rocket fire could resume.
The lull in violence follows a recent Israeli military offensive in which at least 120 Palestinians were killed. Israel says the campaign was aimed at halting militant attacks.
According to Israeli Army Radio Monday, Mr. Olmert has ordered Israel's defense forces to stop air strikes and ground incursions into Gaza as long as Palestinian militants refrain from firing rockets at southern Israel.
Some information for this report was provided by AFP, AP and Reuters.