By Cassandra Garrison

MEXICO CITY (Reuters) -Mexican farmers on Thursday ended a protest at an airport in the northern state of Sinaloa and agreed to meet with the local governor after Mexican President Andres Manuel Lopez Obrador said he would not negotiate with the demonstrators.

Baltazar Valdez, president of the United Farm Workers of Sinaloa, said the hundreds of farmers who have protested at the international airport in the city of Culiacan since Tuesday decided to leave to avoid angering airport users.

"We can't go on because we'll lose the sympathy of civil society, and for us that's very important," Valdez said.

He added that a delegation would meet with Ruben Rocha, the governor of Sinaloa, which is a major corn-producing state.

Producers have urged Mexico's government to guarantee prices for corn, wheat and sorghum to counteract a fall in international prices, and since Tuesday have protested at highways, government offices and the Culiacan airport, where dozens of flights were canceled.

Mexican President Andres Manuel Lopez Obrador said earlier on Thursday he would not negotiate with farmers demanding guaranteed prices for grains, but said he was supportive of small farmers.

"Most people realize that we're helping the producers and the most needy, and we want to support food self-sufficiency," he told his daily news conference.

He accused the protesting farmers of being backed by his opponents in what he described as a "vulgar" display of publicity.

"We're not going to give in, even if they have the airport ... our government does not allow blackmail," he said.

Valdez said many agriculture workers initially supported Lopez Obrador, but no longer believed the president was protecting their interests.

"He is not interested in protecting agriculture ... we are producers and we all contribute to food self-sufficiency," he said.

(Reporting by Daina Beth Solomon and Cassandra Garrison; additional reporting by Sarah Morland Editing by Frances Kerry and Barbara Lewis)