Massachusetts school districts are preparing for higher costs as diesel and heating-oil prices climb, putting pressure on budgets for transportation, meals and heating school buildings. The increases are tied to a global energy crisis following seven months of war in Iran, according to a report published Oct. 12. School officials are concerned the added expenses could push fuel budgets over their limits. “There isn’t a superintendent who isn’t worried about overspending their fuel budget,” said Glenn Koocher, executive director of the Massachusetts Association of School Committees. “I don’t know if anyone has a magic wand to get them out of this.” Some districts may have limited options to respond immediately: school-bus contracts are often set for the year and cannot be renegotiated until the next contract. That could delay budget decisions while fuel costs continue to squeeze public services.