"This afternoon's strike in a densely populated area in the southern suburbs of #Beirut is yet another alarming escalation," Jeanine Hennis-Plasschaert said on X.
Her statement came right after nine people were killed and at least 59 others were injured in an Israeli airstrike in Beirut's Southern Suburb region.
"We are witnessing an extremely dangerous cycle of violence with devastating consequences. This must stop now. A diplomatic way out is still possible," she said.
The strike came after handheld devices and pagers used by Lebanese group Hezbollah detonated Tuesday and Wednesday in Lebanon, killing at least 37 victims, including children. More than 3,000 were injured.
Hezbollah leader Hassan Nasrallah accused Israel on Thursday of breaking "all conventions and laws" and vowed that "retribution will come."
Israel remains on high alert in anticipation of a response from Hezbollah.