A standoff had initially led to the closing of the border.
Mexico has begun allowing migrants and asylum-seekers from a caravan moving north through Guatemala to start crossing into the country.
There were scuffles on the border earlier when dozens tried to force their way across the border and were pushed back by Mexican security forces.
But, under pressure from the White House, the Mexican government says it will try to stop them from carrying on to the US.
Al Jazeera’s John Holman reports from Mexico-Guatemala border.