Volunteers said police stopped them from accessing the area where attackers threw objects and spat on migrants.
Last week the city authorities started to relocate migrants from the shelter at the Benito Juarez Sports Centre to a new facility known as El Barretal due to unsanitary conditions.
Some migrants refused to leave, citing increased distance from the border.
While promising not to carry out any forced evictions, officials cut off services at the Benito Juarez Sports Centre in order to force migrants to leave the area.
Over 5,000 migrants from Central America have been waiting near the US border after travelling over 4,000 km in the migrant caravan. They say they are seeking asylum in the US to escape poverty and violence in their home countries.
