Vandals sprayed graffiti on the walls of the Tzipi Livni Party headquarters in Tel Aviv on Sunday morning, according to a party statement.
The graffiti reads: "Yigal Amir was right," in a reference to former prime minister Yitzhak Rabin's murderer.
The party filed a complaint with the police.
Tzipi Livni on Sunday responded to the graffiti, saying that the words "sharpen our understanding of the struggle we face."
"I did not vote for Rabin," Livni said, "but he was my prime minister. No-one here will murder our democracy or our Zionist dream."