No injuries were reported in either attack, Ynetnews.com reported.
Palestinian sources said Israeli aircraft had fired a missile Monday night at a cell of Hamas' military wing near the Jabalya neighborhood in the northern Strip. Israel said the attack was in response to nine rockets and 13 mortar shells that had been fired on Israel earlier in the day.
Defense Minister Ehud Barak had ordered an easing of the near closure of Gaza crossings Monday, but he hinted at an escalation.
"We must use more and more pressure on Gaza," he said. "What is important is the safety of the residents of the western Negev and Sderot."