Shortly before the army announcement alarm sirens sounded in Tel Aviv and neighbouring towns.
The Israeli foreign ministry posted video of what it said was Israel's Iron Dome missile defence system shooting down one of the incoming rockets "over the Tel Aviv area".
The video showed two outgoing missiles climbing into the sky above high-rise buildings as sirens wail in the background.
Tel Aviv Mayor Ron Huldai told public television one of the Gaza rockets "apparently fell into the sea, the other hit somewhere but not in Tel Aviv."
There were no immediate reports of any casualties or damage.
The station said Prime Minister Binyamin Netanyahu, who is also defence minister, was convening an emergency security meeting at the defence ministry in Tel Aviv.
In October 2018 a rocket fired by Palestinians in Gaza fell into the sea off Tel Aviv and another hit the southern city of Beersheba.
In response to the October fire, Israel struck 20 targets in Gaza, killing one Palestinian, according to the Hamas-run health ministry.
It also closed both its border crossings with Gaza in reprisal, further isolating the blockaded enclave where deteriorating living conditions have stoked violent protests along the border.
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