Israel launched air strikes in Gaza on Wednesday in response to incendiary balloons from the Palestinian territory.
This flareup is a first test for Israel's new government, after a tentative ceasefire stopped 11 days of cross-border fighting last month.
The Israeli military said its aircraft attacked armed Hamas compounds in Gaza in response to their balloons, which the fire brigade reported caused 20 blazes in open fields in communities near the border.
A Hamas spokesman, confirming the Israeli attacks, said Palestinians would continue to pursue their "brave resistance and defend their rights and sacred sites" in Jerusalem.
Only hours before the strikes, there was an Israeli nationalist march in East Jerusalem that drew threats from Hamas, the ruling militant group in Gaza.
Israel, which annexed East Jerusalem after a 1967 war, regards all of Jerusalem as its capital.
However, Palestinians want East Jerusalem to be the capital of a future state that would include Gaza and the West Bank.
Thousands of flag-waving Israelis congregated around the Damascus Gate in Jerusalem's Old City.
Israel has recently beefed up its Iron Dome anti-missile system in anticipation of possible rocket attacks from Gaza.
But as marchers began to disperse after nightfall, there was still no sign of rocket fire.
An earlier march in May was diverted away from the Damascus Gate.
However, that wasn't enough to discourage Hamas from firing rockets toward Jerusalem, an action that seemingly sparked last month's violence.