After two days of unrest over the measure - including one death and dozens of shops ransacked - Maduro on Saturday postponed the measure until Jan. 2.
That helped stem violence, though there were still reports of more lootings in southern Ciudad Bolivar on Sunday.
The detainees include leaders and members of the opposition Popular Will and Justice First parties, Maduro said on state TV, accusing them of following U.S. instructions to incite chaos.
"Don't come and tell me they are political prisoners ... They are the two parties of the 'gringos' in Venezuela," he added, accusing President Barack Obama of wanting to engineer a coup against socialism in Venezuela before leaving office.
From Venezuela's southern jungle and savannah to the Andean highlands in the west, groups of hundreds of protesters have been burning bolivar notes, cursing Maduro and decrying scarcities of food and medicines.
The worst looting was on Friday and Saturday, especially in El Callao and Ciudad Bolivar in the southern state of Bolivar, and police have used teargas to control crowds in some places.
Chinese-run shops have been particularly targeted, witnesses say, and a 14-year-old boy was shot dead in El Callao on Friday.