Emergency services spokesman Ashraf al-Qidra said the first strike targeted a coffee shop in the city of Khan Younis, killing six men and wounding at least 15 others, AFP reported.
The second strike hit the home of Raed Shalat at Nuseirat refugee camp in central Gaza, killing him and injuring several others, Qidra added.
Seven people – three women and four children – were killed in further strikes on two houses in Khan Younis. The Palestinian Health Ministry said five of those killed were children. Another 16 people were also wounded in the attack, the ministry added.
Meanwhile, Israel Defense Forces (IDF) says over 360 rockets have been fired at Israel since the beginning of Operation Protective Edge. Over 590 targets in the Gaza Strip were hit.
The offensive is the worst escalation of violence between Israel and the Palestinians since 2012.
Palestinian rockets have targeted central and southern Israel, reaching as far as Jerusalem but causing no serious casualties.
UN Secretary-General Ban Ki-moon will give a briefing at an emergency meeting of the Security Council on Thursday around the escalating Israeli-Palestinian violence. "Gaza is on a knife edge," Ban told reporters on Wednesday. "I firmly condemn the multiple rocket attacks launched from Gaza on Israel. Such attacks are unacceptable and must stop."
"I also urged [Israeli] Prime Minister [Benjamin] Netanyahu to exercise maximum restraint and to respect international obligations to protect civilians. I condemn the rising number of civilian lives lost in Gaza," he added.
Palestinian rescuers check a car hit by an Israeli air strike killing the driver in Gaza City on July 9, 2014. (AFP Photo / Thomas Coex)