Parliament in Jakarta was to meet in an emergency session on Thursday in order to overturn one decision made by the country's Constitutional Court on election procedures, while amending another.
Protesters held banners and signs, while others started a fire and burned tyres.
The Constitutional Court court on Tuesday dismissed a challenge to an age limit that prevents people younger than 30 running for regional governorships, which would prevent the Widodo's 29-year-old youngest son, Kaesang Pangarep, running in a regional contest in Central Java.
The court also made it easier for political parties to nominate candidates by cutting back a requirement they hold 20 per cent of a local legislature.
Protesters fears the law changes could further enhance the influence of outgoing President Widodo. (AP PHOTO)
Parliament passed an emergency motion to changing the minimum age to serve as governor to 30 at the time of inauguration and further ease nomination requirements on Wednesday, and planned to ratify the vote in a plenary session on Thursday.
The moves triggered widespread condemnation on local social media and raised concerns about a potential constitutional crisis.
The legislature was forced to delay the vote after failing to achieve a quorum.
Widodo's eldest son, Gibran Rakabuming Raka, is the incoming vice-president after the same court created an exception to the age limit for the post for former regional leaders, while Widodo's brother-in-law was serving as chief justice.
He was criticised for taking part in a case involving a close relative and later dismissed.
Activists, students, workers, and a number of Indonesian celebrities and musicians also joined the protest, voicing concerns about democracy in Indonesia.
Protests were also reported in other big cities, including Bandung, Yogyakarta, Surabaya and Makassar.
Their demands included voting down the regional election bill, respecting the Constitutional Court's ruling and rejecting political dynasties.
The simultaneous protests in the major cities showed anger at parliament's efforts to overruled the Constitutional Court decision to allow more candidates to compete in the regional elections, said Yoes Kenawas, a political analyst at Atma Jaya Catholic University.
"They also opposed the dynastic politics carried out by President Jokowi," Kenawas said.
