Nadal, who recently returned to the court after a seven-month injury layoff, needed just 68 minutes to oust Schwartzman, who at 20 was the youngest player in the men’s draw.
The 11-time Grand Slam champion Nadal advances to the second round, where he is to face his second consecutive Argentinean qualifier, 27-year-old Martin Alund.
Nadal improved to 34-1 on clay against players ranked outside the top 100 as he makes his first appearance in Acapulco since claiming the title eight years ago. Schwartzman is ranked 157th in the world.
Nadal was off for seven months with persistent knee problems and has been testing his fitness in clay tournaments this month before he switches to hardcourt events.
He won his 37th clay-court title earlier this month in Sao Paulo, Brazil, beating David Nalbandian in the final.
On Tuesday, a Spanish newspaper reported that world No. 5 Nadal would miss the upcoming ATP World Tour Masters Series events in Indian Wells, California, and Miami, Florida.
Nadal’s camp and tournament organizers dismissed the report.