Thousands of people marched to the Pacific resort town's international airport, with parents of the students leading the demonstration along with comrades from the 43 young men's teacher-training college in the southern state of Guerrero.
The rally followed violent protests that erupted over the weekend after authorities said gang hitmen confessed to murdering the 43 students and incinerating their bodies in September after corrupt local police handed the men over.
In a case causing national revulsion, Attorney General Jesus Murillo Karam downplayed chances of ever identifying the charred remains, warning that only two bones were salvageable for DNA tests.
The protesters blocked the airport's entrance for more than three hours, with some masked men armed with sticks, though several tourists snuck in through a private terminal.
Before reaching the airport, protesters threw stones and a firebomb at riot police who were blocking their way, injuring at least 20 officers, a security official said.
Tourists had to reach the airport by foot, pulling their suitcases behind them. Three flights were canceled.