President Obama said Sunday he is determined to work with Israel in “lock step” to prevent Iran from developing nuclear weapons, and tried to allay concerns that Israel is preparing to carry out a unilateral military strike. “I don’t think that Israel has made a decision on what they need to do,” Mr. Obama said during an interview at the White House during NBC’s Super Bowl pre-game show. “We are going to make sure that we work in lock step, as we proceed to try to solve this — hopefully, diplomatically.”