Israel closed its crossings with the Gaza Strip on Tuesday, the military said.
A military spokeswoman said only pedestrian traffic would be permitted through until further notice.
Palestinians fired a rocket at southern Israel on Monday evening.
No group claimed responsibility and no injuries or damage were reported.
The truce went into effect on June 19, the crossings have been closed for five days.
Palestinian officials said the latest border closure meant a long-awaited shipment of cement would not be allowed through.
Also Tuesday, the Gaza Strip's border with Egypt was due to open for two days to let hundreds of people stranded on both sides to cross.
Egyptian diplomat Nabil Amr told reporters in Cairo on Monday that Palestinians needing medical treatment would be allowed into Egypt, as would those with residency permits in Egypt or elsewhere.
Palestinians returning from abroad would be allowed into Gaza from Egypt, he said.
Amr said that the opening of the border was a "humanitarian" decision in response to appeals from Palestinians stranded by border closures.
Last Mod: 01 Temmuz 2008, 11:40