Demonstrators gathered in central Khartoum chanted slogans against an agreement between the military chief Abdel Fattah al Burhan and the reinstated Prime Minister Abdalla Hamdok.
Sudanese security forces have fired tear gas at protesters rallying against last month's military takeover and a deal that saw the prime minister reinstated.
Thousands of demonstrators gathered in central Khartoum on Tuesday and marched on the presidential palace when security forces fired tear gas to disperse them.
"No partnership, no negotiation, no legitimacy," protesters chanted, urging the military "to go back to their barracks".
Sudan's top general, Abdel Fattah al Burhan, seized power and detained Prime Minister Abdalla Hamdok on October 25, but after international condemnation and mass protests he reinstated the premier in a deal they signed last week.
Critics lambasted the agreement as "whitewashing" and accused Hamdok of "betrayal" as pro-democracy activists vowed to maintain pressure on the military-civilian authority.
At least 43 people have been killed in anti-coup protests since last month, according to medics.
Doctors have accused security forces of using live rounds but police denied the allegations saying it only used "minimum force" to disperse protests.
The Sudanese Professionals Association (SPA), an umbrella of unions which called for Tuesday's protests, accused Hamdok and Burhan of seeking to "reproduce the former regime" of president Omar al Bashir, who was ousted in April 2019 following mass protests.
"Taking to the streets is a clear and decisive response to the putschists' nonsense," said the SPA, which was also involved in the anti-Bashir protests.
Hamdok, who has been prime minister in the transitional government since the ouster of long-time autocratic ruler Bashir, has defended the deal which was signed on November 21.
The Burhan-Hamdok agreement was welcomed by the United Nations, African Union, Western countries as well as Arab powerhouses Saudi Arabia and Egypt, which have strong ties with the Sudanese military.
The military has vowed to release detainees kept in custody since the coup and several politicians have since been freed.
Burhan has also pledged to lead Sudan to "free and transparent elections" in July 2023.