Israeli shells on Tuesday also killed a Palestinian in the north of the strip after rocket attacks on Israel.
The missile attack in Gaza City wounded a policeman. Hamas said Israel was trying to send a message in response to the Islamic group's victory in January parliamentary elections.
Israel said it was responding to Palestinian cross-border rocket attacks.
Israel's YNet website said one of about a dozen projectiles fired from Gaza landed in an industrial area on the outskirts of the Israeli coastal town of Ashkelon, narrowly missing a storage area for inflammable materials.
The Israeli military said it had carried out two separate air attacks, one on an open field in northern Gaza from where resistance fighters fire rockets, and the other on an "open, unpopulated space" in Gaza City.
In the northern Gaza town of Beit Lahiyeh, separate Israeli fire killed at least one person and wounded about seven others, including several in a house, Palestinian security officials said.
Launch sites hit
One of those wounded in the house was a four-month-old girl, Reuters television pictures showed.
An Israeli army spokeswoman said artillery fire targeted rocket launching sites.
"There was no intent to hit any homes and we have no knowledge that we struck any," she said.
Hamas leaders have decried
the Israeli attacks
Earlier, Palestinian witnesses said two missiles fired from the air struck a training base used by Palestinian security forces in Gaza City. The office of Mahmoud Abbas, the Palestinian president, is nearby, although he was not there at the time.
"There is no justification for these operations. We do not understand them," Abbas told reporters in the West Bank city of Ramallah. "We have appealed to the United Nations, Russia, the EU (European Union) and our Arab brothers, telling them that these actions will severely complicate civil life."
Hamas spokesman Sami Abu Zuhri, also commenting on the air strike, said: "The continuation of aggression will only bring more destruction and death on the enemy."
On a different issue, speaking to Aljazeera on Tuesday, Omar Abd al-Raziq, the Palestinian finance minister, denied any knowledge of an Israeli bank decision to block money transfers to the Palestinian Authority.
Israel's Yediot Aharonoth paper published a report saying that the the bank decided to suspend all international transfers to the PA after the Hamas government was sworn in.