The workers protested at the Jantar Mantar and raised slogans against the Bharatiya Janata Party (BJP) and Prime Minister Narendra Modi.
"The way the BJP has hiked diesel and petrol prices and wants to increase the price of other commodities has made it clear the party doesn't want to work for the people. Before the (Lok Sabha) elections, the BJP had promised to bring down the prices of oil and other commodities. But they are not keeping their promise and are cheating the public," Delhi Congress president Arvinder Singh Lovely told reporters.
"If it is not possible for the BJP to lower the prices, then at least they should try to keep the prices of oil and petrol same," he added.
A Delhi Police official said: "We detained 40-50 Congress workers to prevent the situation from going out of control." He added they were later released.