MEXICO CITY (Dow Jones)--The Mexican peso firmed slightly against the U.S. dollar Thursday, taking breather after a two-session fall thanks to positive U.S. jobs data, although uncertainty and caution over the euro's future remain high.

Mexico ’s peso gained for the first day in four after a Spanish bond auction eased concern over Europe’s debt crisis and U.S. unemployment claims fell to a three-year low, boosting the outlook for growth in Latin America’s second-largest economy.

MEXICO CITY--The Mexican peso retreated against the U.S. dollar Thursday as European sovereign debt worries returned after Spain's and France's borrowing costs soared.