There - at the far end of the bridge over the Suchiate River, which forms the western part of the Mexico-Guatemala border - they hurled rocks and other objects at hundreds of riot police, who responded with rubber bullets and tear gas.
Some planned to walk toward Mexican territory in a formation that put the men along the edges and women and children in the center.
He also warned the migrants that they should turn back. Some violently shook fences.
Migrants have been known to cross the river on rafts for years - sometimes encountering authorities along the way, sometimes meeting little resistance as they slipped into Mexico and continued their journey north. Others turned back towards Guatemala.
Since the mid-1970s, migrants from Central and Southern America have exploited Mexico's relatively lax policies on border security to enter the USA illegally.
The march of the migrant has swollen now to 4,000 people, mostly Hondurans.
The migrants have no fresh supplies of water or food and slept amid garbage that has piled up at the crossing.
Mexico's federal government Thursday deployed 200 police agents to its southern border in the state of Chiapas to stop Honduran migrants from entering the country without visas.
But the slow pace frustrated those stuck on the bridge, where conditions were hot and cramped, and some pleaded at the main gate: "Please let us in, we want to work!" "Meanwhile, we must accompany our fellow countrymen", he said on Friday. Guatemalan troops are also said to be putting up resistance.
The migrants defied the request, however, and about midday local time, the throng - now numbering in the thousands -moved toward the border crossing, coming to a stop at the closed Guatemalan border fence.
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On Friday morning, however, Mexican officials, including the country's ambassador to Guatemala, circulated through the crowds of migrants, appealing for order and inviting them to present themselves at the border one by one, where they would be processed by migration authorities. "We don't want them", Trump said.
The 25-year-old farmer had no blanket to fend off the chill, but vowed to continue on. And if we go back to Honduras we'll suffer until the day we die.
He said that he makes 150 lempiras a day, or about $6 U.S., and has no work benefits. More than 150 members of that group crossed the border and sought asylum. On Friday, they broke down Guatemalan gates and streamed toward a bridge to Mexico.
BBC journalists spoke to some of the migrants travelling with the caravan as they wait at the border.
A chaotic scene unfolded as a massive caravan of Honduran migrants reached the Guatemala-Mexico border Friday.
"Guatemala has always been known as a major smuggling corridor for foreigners from African and Asian countries making their way into the U.S", Judicial Watch said Friday.
Though it began with just a couple hundred Hondurans headed for the United States, the support flowing in from leftist organizers and funders has grown this new caravan of hopeful immigrants into the thousands.
"In Mexico, we have the rule of law, and we shall apply-enforce the law, but there will also be a humanitarian way that we will think about the migrant in the first place", said Mexican Foreign Secretary Luis Videgaray, minister of foreign affairs, to reporters in Mexico City.
Honduran President Juan Orlando Hernández said via Twitter on October 19 that he had asked permission from Guatemalan President Jimmy Morales to send Honduran civil protection personnel to the bridge to help the migrants. The US no longer has to house them until their cases are heard.