A teenager and five Hamas militants were among the seven killed, including one senior member, Louay al-Borno, who died when a minivan was struck in Gaza City. Two other Hamas members were wounded in the incident.
Israel says it is targeting militant but Palestinian officials accuse Israel of carrying out a "massacre".
Palestinian Authority President Mahmoud Abbas has urged the UN Security Council to convene to discuss the issue.
An Israeli military spokesman said five air strikes had take place, targeting the towns of Beit Hanoun, Beit Lahiya , Jabaliya and Rafah.
Israeli forces have made regular incursions into Gaza and the West Bank following the capture of an Israeli soldier in a cross-border raid by Palestinian militants on June 25.