The Israeli military on Monday said it struck an underground militant infrastructure site in Gaza in response to rocket fire toward Israel.
The airstrikes came amid days of renewed tensions and violence along the Gaza border. The military has struck various targets in Gaza in recent days and killed two Palestinians who tried to infiltrate Israel after a militant bomb on the border wounded four Israeli soldiers.
Israel holds Gaza's militant Hamas rulers responsible for all attacks emanating from the territory, regardless of who carries them out. There were no immediate reports of casualties from the strike on the underground site.
The border area has been generally quiet since a 50-day war between Israel and Hamas in 2014. But it has seen an increase in violence since President Donald Trump's announcement in December recognizing Jerusalem as Israel's capital.
Trump: Palestine Must Cooperate With Israel for US Aid
European Commission spokeswoman Maja Kocijancic said the escalating violence was of "real concern."
In a statement, she called rocket fire at Israel "unacceptable" and said the European Union acknowledges Israel's "legitimate security concerns." Nonetheless, she expressed hope the situation does not further escalate and called on all parties to "act with restraint."