Israeli aircraft have bombed tunnels used by smugglers under Gaza's border with Egypt, killing one Palestinian.
The raids came shortly after militants in Gaza fired a rocket and eight mortar rounds into southern Israel - the highest daily total in over a year.
The rocket struck near the Israeli city of Ashkelon, but caused no casualties or major damage, the military said.
There has been an upturn in violence since the resumption of peace talks earlier this month.
It follows months of relative calm since the Israeli offensive, known as Operation Cast Lead, which ended in January 2009.
It was aimed at halting attacks on Israel from Gaza, but cost the lives of more than 1,400 Palestinians and 13 Israelis, including three civilians.