MEXICO CITY—Mexico is confident that an agreement on a major free-trade pact spanning the Pacific Ocean can be reached in late July in what would be a milestone with the potential to reshape economic ties between Asia and the Americas, a top government official said Monday.

“Around 10% of issues are still to be agreed, but I hope we can seal an agreement in a final round of negotiations at the end of the month,” Economy Minister Ildefonso Guajardo said in an interview. He said leaders could sign an agreement before the end...