An Israeli air strike on southern Gaza killed an Islamic Jihad militant and wounded another early on Wednesday, Palestinian medical officials said.
The attack targeted two Palestinians on a motorbike near the southern city of Rafah who were en route to pray, said a statement from Islamic Jihad's military wing, the Al-Quds Brigade.
A second attack hit a cross-border smuggling tunnel in the area, Palestinian security sources said.
The raids came just hours after a rocket landed in southern Israel, causing no casualties, despite a weekend agreement by Gaza militants to curb rocket fire.
An Israeli military spokeswoman confirmed an attack on "a group of terrorists" who had fired the rocket into southern Israel on Tuesday evening, saying they were en route to fire more.
The violence comes after several days of relative calm, punctuated by an Israeli air strike on Sunday morning which killed another two Jihad militants who the army said were preparing to fire rockets at Israel.
The Al-Quds Brigades had vowed to respond.
A day earlier militants had agreed to observe a period of calm, effectively calling a halt to 10 days of rocket attacks and Israeli counter strikes.
Despite the tension in and around Gaza, both Israel and Hamas appear reluctant to be dragged into another bloody war confrontation along the lines of the deadly 2008-2009 war, which killed more than 1,400 people, the vast majority Palestinians.
That 22-day offensive was launched by Israel in order to stamp out persistent rocket fire from Gaza.