Around 2,000 Honduran migrants are said to be camped out in eastern Guatemala after security forces used sticks and tear gas to stop their passage towards the US.
The authorities said that as many as 8,000 migrants, including families with young children, have entered Guatemala since Friday.
The caravan has been trying to flee poverty and lawlessness in a region which has been rocked by the COVID-19 pandemic and back-to-back hurricanes in November.
Officials in Guatemala said they have sent back hundreds of migrants to Honduras, but many have set up camp about 34 miles (55km) from the borders of Honduras and El Salvador after clashing with the security forces at the weekend.
One man, who gave his name as Pedro, said: "There's no food or water, and there are thousands of children, pregnant women, babies, and they don't want to let us pass."
A mother, travelling with her 15-year-old son, nine-year-old daughter and four-year-old niece, said: "We're starving. All we have is water and a few cookies."
Other migrants have tried to evade the gridlock by fleeing into the hills to continue heading towards the border of Mexico, where the government has deployed police and troops.
Thousands of the migrants had left the Honduran city of San Pedro Sula on Thursday to travel north in a bid to reach the US border.
As they moved across Guatemala towards its border with Mexico, they clashed with soldiers and police close to the village of Vado Hondo.
"These types of illegal mass movements (of people) will not be accepted, that's why we are working together with the neighbouring nations to address this as a regional issue," the Guatemalan president's office said in a statement.
The caravan comes ahead of Wednesday's inauguration of Joe Biden, who migrants are hoping will be more sympathetic to their plight than the outgoing president, Donald Trump.
An official in Mr Biden's transition team advised people not to make the "extraordinarily dangerous" journey towards the US.
"Overcoming the challenges created by the chaotic and cruel policies of the last four years, and those presented by COVID-19, will take time," the official added.
In 2018, a group set off from San Pedro Sula towards the US, prompting Mr Trump to use his Twitter account to falsely claim "criminals" were heading towards the border.