Pope Francis is condemning what he calls an "unacceptable" attack on a Jerusalem synagogue and is calling for Israel and the Palestinians to take "courageous" steps to forge peace.

Francis told his weekly General Audience on Wednesday that he was greatly concerned by the "alarming increase in tensions" in the Holy Land. Two Palestinian cousins carried out the attack Tuesday, killing five people. Israel has vowed retaliation.

Francis, who hosted the Israeli and Palestinian presidents for a daylong peace prayer in the Vatican gardens last summer, said he was praying for all victims.

He urged both sides to end the "spiral of hatred and violence and take courageous decisions for reconciliation and peace." He said: "To build peace is difficult, but to live without peace is a torment."