The Israeli army said it was closing to civilian traffic three roads that lead to, or border the Gaza Strip, in an indication of a probable military build-up in the area.
Shortly before, political sources said Defence Minister Ehud Barak was seeking government approval to mobilise up to 75,000 reserve troops for Israel's Gaza campaign, in a sign of preparations for a possible ground offensive.
Today's bombing in Tel Aviv is reminiscent of six years ago and could mark a serious escalation in the conflict.
A truce in Gaza suits all sides but none of the groups seem interested in a long-lasting solution.
A complex system of air defences has been instrumental in protecting Israel's population from incoming rockets.