Protesters torched six buses and trucks that had defied the strike, police spokesman Ganesh Chetri said. Police arrested 51 people.
Most schools, private businesses and shops were closed out of fear of retaliation, and riot police and soldiers patrolled the streets.
Government workers were forced to walk to their jobs. The nation's only international airport, in Katmandu, was functioning normally, but passengers had to walk to it with their luggage.
Srijana Tamang, a housewife who was walking to the airport, bemoaned the political paralysis.
"It is the people who suffer for no reason," she said.
Next week's election is intended to create a Constituent Assembly to write a new constitution.
A previous assembly was tasked with writing the constitution in 2008, following the overthrow of the country's centuries-old monarchy. But the assembly was riven by political battles and never accomplished its task.
The alliance of opposition parties that called the strike is demanding the present interim government, led by the Supreme Court's chief judge, be disbanded and a new government with representation from all the political parties formed to conduct elections at a later date. The present government was formed earlier this year by the major political parties.