One Palestinian was killed and four others wounded in the strike on a vehicle carrying militants in the southern town of Rafah.
An Israeli army spokesman said the raid targeted militants who had fired several mortar rounds against southern Israel that caused no injuries.
Late yesterday, Israeli fighter jets launched air strikes across Gaza in response to the rocket fire.
The strikes have shaken the 18 January ceasefire that ended Israel's 22-day war against Gaza.
There were no reports of casualties from yesterday's strikes, which hit a Hamas police station and tunnels between Gaza and Egypt.
Israeli Prime Minister Ehud Olmert vowed yesterday to deal 'a severe and disproportionate Israeli response' to the new rocket fire.
More than 15 rockets have been fired from Gaza since the end of Operation Cast Lead, wounding one civilian and two soldiers, Israel said.
Defence Minister Ehud Barak said that although most of the rockets were not fired by Hamas, the Islamist movement which has controlled Gaza since June 2007 bore responsibility for the attacks.
