Shoppers tempered their spending in April as higher gas prices fueled by the Iran war meant less money left over for some nonessentials like clothing and furniture. But they’re still buying, thanks to more generous tax refunds. Still, economists worry that spending will fall off more dramatically in the coming months as benefits from the refunds dissipate, and shoppers continue to grapple with the cumulative impact of rising gas prices at the pump. Retail sales rose 0.5% in April, a slowdown from the revised growth level of 1.6% in March, according to Commerce Department data released Thursday. March marked the largest one-month increase in retail spending in more than three years, largely because gas prices spiked higher rapidly.