Israel says it is currently carrying out "extensive strikes on terror targets" across the Gaza Strip.
A statement from Prime Minister Benjamin Netanyahu's office added that "from now on, Israel will act against Hamas with increasing military force".
There have been fatalities and injuries as a result of the strikes, a spokesman for the Palestinian Civil Defence added.
According to the prime minister's office statement, Mr Netanyahu and defence minister Yisrael Katz ordered the Israeli Defence Forces (IDF) to "act forcefully" against Hamas.
The order came after the militant group "repeatedly refused to release our hostages and rejected all offers it received from the US presidential envoy, Steve Witkoff, and from the mediators".
The statement then added: "From now on, Israel will act against Hamas with increasing military force. The operational plan was presented late last week by the IDF and approved by the political echelon."
A joint IDF and Shin Bet (ISA) statement also said they are "currently conducting extensive strikes on terror targets belonging to the Hamas terrorist organization in the Gaza Strip".
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The IDF strikes come two days after the Gaza health ministry said nine Palestinians, including three journalists, were killed in an Israeli airstrike in the northern town of Beit Lahia.
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