The militant group Hamas says seven of its fighters have been killed by a series of Israeli airstrikes in the Gaza Strip.
A Hamas statement Monday said four people were also injured, and vowed that Israel would "pay a tremendous price" for the attacks.
The Israeli military said it carried out airstrikes overnight in response to what it said were 25 rockets fired by militants in Gaza into Israel. It also reported clashes early Monday after security forces were attacked near a security fence in Gaza.
On Sunday, Israeli Prime Minister Benjamin Netanyahu reiterated appeals for calm, and vowed to not allow extremists from either side to "set the region on fire and bring a new wave of bloodshed."
Israeli-Palestinian tensions have increased in recent weeks following the deaths of three kidnapped Israeli teenagers and that of a Palestinian teen who was kidnapped and burned to death in an apparent act of revenge.