Guijarro's first international youth tournament experience came when she was fifteen, with a callup to play for Spain at the 2013 UEFA Women's Under-17 Championship. She played all 90 minutes of Spain's two matches in the finals. The first finals match against Sweden went to penalties, and despite her penalty conversion, Spain lost the shootout 4–5. They got some compensation, however, by defeating Belgium 4–0 in the next match. Guijarro scored Spain's third goal of the match as they bowed out as third-place finishers.