"Enemies of peace" were to blame for Tuesday's gun attack in Israel which left four Israelis dead, the European Union's foreign policy chief, Catherine Ashton, said Wednesday in a statement condemning the violence, DPA reported.
Israelis and Palestinians are set to meet in Washington later on Wednesday for the first direct peace talks in over a year.
"With this unacceptable attack, the enemies of peace have tried to derail the Middle East peace talks. But we are determined not to let these enemies of peace have their way," Ashton said in a statement.
Israel, the Palestinian Authority and the United States have already condemned the attack and vowed that it will not derail the talks. But Israeli settlers said Wednesday that they would end a freeze on construction in the occupied West Bank in retaliation for the killings.
Such a move could itself endanger the talks, as the Palestinians have repeatedly demanded an end to settlement activity.
"I call upon the parties of the talks ... to engage with determination in the negotiations. It is imperative that both parties keep calm and exercise restraint even through difficult times to make progress towards a just, lasting and comprehensive peace in the region," Ashton said.
Ashton represents the EU's 27 member states and is also vice-president of the bloc's executive, the European Commission, which manages the EU's trade and aid policies.
She made her comments while on a visit to China ahead of an EU summit dedicated to discussing relations with the new superpower. Some EU politicians have criticised her for not attending the Washington talks instead.