Israel's air force hit a Hamas base in the Gaza Strip on Monday, the military said, as bloody clashes between protesters and soldiers raged along the strip's border with Israel.
"A fighter jet struck five terrorist targets in a military training facility belonging to the Hamas terror organisation in the northern Gaza Strip," a military statement said.
"The strike was conducted in response to the violent acts of the last few hours being carried out by Hamas along the security fence."
The border clashes left at least 37 Palestinians dead from Israeli fire and hundreds wounded in the conflict's bloodiest day in years.
The dead included a 14-year-old, according to the Gazan health ministry, which also provided the overall death toll.
The Israeli army said that earlier a warplane and a tank fired at other Hamas "military positions" after Hamas gunmen allegedly fired at Israeli forces.
There had already been weeks of protests and clashes along the Gaza border, with at least 91 Palestinians killed by Israeli fire there since March 30.
No Israelis have been wounded and the military has faced criticism over the use of live fire.
Monday's surge in violence came as a White House delegation and Israeli officials gathered for the contentious inauguration of a US embassy in Jerusalem.
It was the bloodiest day in the Israeli-Palestinian conflict since a 2014 Gaza war..