Sudanese demonstrators wave flags during a rally in Khartoum Bahri, on December 6, 2021. AFP
It was the latest rally in recent weeks by Sudanese opposed to a military-dominated government in the country where top general Abdel Fattah al-Burhan seized power in October.
Monday's protesters in Khartoum waved Sudanese flags and changed "civilian is the people's choice" as well as "the people are stronger".
Witnesses said protests were also underway in parts of eastern Sudan, including Kassala and Gadaref states.
"Protesters are in the centre of the city and are chanting 'no to military rule'," Kassala resident Mohammed Idriss told AFP.
Speaking from Gadaref, resident Amal Hussein said around 600 protesters rallied there, where they also waved Sudanese flags and chanted slogans demanding civilian rule.
Following the October 25 military takeover, previous protests were met by a violent crackdown that left 44 people killed and hundreds wounded, mostly by bullets, according to a pro-democracy doctors' union.
On that day Burhan seized power and detained Prime Minister Abdalla Hamdok but reinstated him in a deal signed on November 21 after international condemnation and mass protests.
Critics lambasted the agreement and pro-democracy activists vowed to maintain pressure on the military-civilian authority.
Burhan has insisted that the military takeover was "not a coup" but a step "to rectify the transition" towards full democracy that started with the 2019 ouster of autocratic president Omar al-Bashir.
He has pledged to lead Sudan to "free and transparent elections" in July 2023.