The killing of seven Palestinian civilians on a Gaza beach Friday will likely cast a heavy cloud over Prime Minister Ehud Olmert's trip to Europe, diplomatic officials said Saturday night. Olmert leaves Sunday for Britain, where he is scheduled to meet Prime Minister Tony Blair on Monday. He will then fly to France Tuesday for a meeting with President Jacques Chirac and other senior officials. He is scheduled to return on Thursday. The trip is part of Olmert's efforts to drum up support for his realignment plan - efforts that have already taken him to Washington, Egypt and Jordan and that will see him visit Germany next month. However, he is now likely to face tough questioning in Britain and France over the IDF's policy of shelling Gaza in response to Kassam rocket fire on the Negev. Both the British and French foreign ministries issued statements condemning Friday's incident and calling on Israel to exercise restraint. The UK Foreign Office issued a statement that said: "We are deeply concerned by reports of the deaths from Israeli shelling of civilians, including children, on a Gaza beach this afternoon. The killing of innocent civilians is utterly unacceptable and we urge the Israelis to undertake an investigation into this incident." Foreign Secretary Margaret Beckett said she would raise the issue when she meets Foreign Minister Tzipi Livni in Luxembourg. Livni is traveling there for two days of talks with European foreign ministers on Monday. The French Foreign Ministry issued a statement saying it "deplores the Israeli bombing on a beach in the Gaza Strip, whose disproportionate character cost the lives of several civilians and injured many others." Israeli officials expressed regret that the world had already determined who was responsible for the deaths, even before an investigation had been concluded. One official said it was not beyond the realm of possibility that the deaths were caused by an errant Kassam missile that "fell short." US Secretary of State Condoleezza Rice phoned Livni over the weekend to discuss the situation. Livni, according to officials in her office, told Rice that Israel was only engaged in military operations in the Gaza Strip because the Palestinian Authority was unwilling to dismantle the terrorist infrastructure and prevent the Kassam fire. She also expressed Israel's regret at the loss of civilian lives. Livni told Rice that Hamas members are increasingly involved in the firing of Kassam rockets. The US called on Israel and the Palestinians Saturday to refrain from actions that would lead to further escalation in the Gaza Strip. In a statement issued by the State Department, spokesman Sean McCormack said, "The United States calls for mutual restraint and urges Israelis and Palestinians to avoid all actions that could exacerbate tensions further." The US did not condemn Israel for the attack, though it did make clear that it viewed the IDF as responsible for firing the shells that led to the deaths of the Palestinians. "The United States expresses its regret for the killing and wounding of innocent Palestinians in Gaza today as a result of artillery fire by the Israeli Defense Forces," the statement read. At the same time, the US noted the regret expressed by the Israeli government and the actions taken following the incident. "We welcome Israel's announcement that it has suspended artillery fire while that investigation continues." The US called on the PA to prevent "all acts of terrorism, including the firing of missiles and rockets" from the Gaza Strip. In advance of his trip to Europe, Olmert, in an interview with Britain's Independent newspaper published Saturday, dismissed PA President Mahmoud Abbas's call for a referendum on establishing a Palestinian state. "The referendum is an internal game between one faction and the other," he said. "It is meaningless in terms of the broad picture of chances towards some kind of dialogue between us and the Palestinians. It's meaningless. "Mr. Abbas will not be able to get away by saying I forced a referendum that accepted a program which is far behind the basic principles that the international community [has] defined anyway." Israel has said that the so-called prisoner's document that is the basis for the referendum, which calls for a Palestinian state based on the pre-1967 lines with east Jerusalem as its capital and a right of refugee return to Israel, is unacceptable. In another interview, this one with Britain's Sky Television for broadcast Sunday, Olmert reiterated his position that Israel wants to negotiate with the PA, but will take unilateral action if need be. "I am ready to make concessions that will be painful and divisive, the specific nature of which, the accurate aspect of all this will take place during the process of negotiations," he said. "I'm not going to negotiate on television, but I'm ready to make these sacrifices and I spelled it out to the public opinion of my country prior to the elections, and it cost me many votes, but I got a clear mandate and I'm ready to go," he said. Olmert told Sky that during talks with Blair he would seek his help to "facilitate this process that will hopefully force the Palestinians to change their minds so that they will be ready for the negotiations as well." "We want to negotiate with Abu Mazen [Abbas], we will be meeting with him and I plan to see him later this month and see what I can do to help him," Olmert said. "But if it will be agreed by the international community that conditions have not matured to allow negotiations, which is the case now, then the question is, what shall we do? Wait forever? Do nothing? Keep a stalemate, freeze the situation? "Or shall we try to do something that will move things forward that will help create an environment of better understanding? That's what I'm interested in doing and I don't think that we should wait too much," he said. "If it will be in 2007, if it will be in 2008, if it will be earlier or later, when the time will come, one thing must be clear: We are not going to keep the status quo forever. We want to move, we want to change. We want to create better conditions for peace in the Middle East," Olmert said. Nathan Guttman and AP contributed to this report.