DA marchers taking part in the march against Cosatu in Johannesburg took off their blue shirts in fear of Cosatu supporters as police fired teargas on Tuesday morning.
While marching down Jorissen Street in Braamfontein, they were met head-on by Congress of SA Trade Unions (Cosatu) supporters wearing red T-shirts.
Cosatu supporters were intimidating the DA supporters and not allowing them to pass as they headed towards Cosatu House.
Police fired teargas at Cosatu supporters to try to control the crowd.
Several hundred people wearing blue T-shirts converged on Beyers Naude Square in the city centre to protest against the union federation's opposition to the youth wage subsidy.
Democratic Alliance leader Helen Zille, youth leader Makashule Gana, parliamentary leader Lindiwe Mazibuko and national spokesman Mmusi Maimane led the protest.
The planned route was along President, Rissik, Jeppe, Sauer, Burger, Jorissen, Melle, and Simmonds streets.
Meanwhile, Cosatu supporters in red T-shirts waited outside the federation's offices.
"We are here to welcome the DA when they arrive," Cosatu spokesman Patrick Craven said.
Earlier, police said the protesters could not end their march outside Cosatu House in Braamfontein. Instead it was agreed they would finish at least 50m away, on the lawns of the Joburg (formerly the Civic) Theatre.
The DA believes the youth wage subsidy will create at least 423,000 jobs for young, unemployed South Africans.