Protesters planned to march on President Omar al-Bashir's palace calling for him to "step down" following deadly anti-government protests.
Opposition groups and prominent rebel chief Abdel Wahid al-Nur from war-torn Darfur have also urged their supporters to participate in the march.
Bashir has instructed police to abstain from using excessive force against the demonstrators after 19 people, including two security personnel.
Riot police deployed in key squares of Sudan's capital Monday as protesters planned to march on President Omar al-Bashir's palace calling for him to "step down" following deadly anti-government protests.
Bashir has instructed police to abstain from using excessive force against the demonstrators after 19 people, including two security personnel, were killed in clashes in the initial days of demonstrations that erupted on December 19.
Angry protesters have rallied after the government raised the price of a loaf of bread from one Sudanese pound to three (from about two to six US cents).
Protests that erupted against high prices of bread have turned into anti-government rallies in Khartoum and several other cities.
On Monday, a group bringing together professionals like doctors, teachers, professors and engineers called for a march from downtown Khartoum to the presidential palace after a similar rally it organised on December 25 in the capital.
"We are again calling for a rally on December 31 at 1:00 pm (1100 GMT)," the group calling itself as Sudanese Professionals' Association said in a statement late Sunday.
"We will march towards the presidential palace calling for President Omar al-Bashir to step down."
Opposition groups and prominent rebel chief Abdel Wahid al-Nur from war-torn Darfur have also urged their supporters to participate in the march.
An AFP journalist who toured downtown Khartoum early Monday saw dozens of anti-riot policemen and security agents of the powerful National Intelligence and Security Service (NISS) deployed to prevent any gathering of protesters.
On Sunday, Bashir met top police officers in Khartoum and instructed them to refrain from using excessive force against demonstrators after the United Nations called for an investigation into the deaths and violence during the demonstrations.
"We want to maintain security and we want the police to do that by using less force," Bashir said.
"We admit that we have economic problems... but they can't be solved by destructions, lootings, and thefts," Bashir said, referring to the buildings and ruling offices torched by protesters in several cities during the demonstrations.
Sudan is facing an acute foreign exchange crisis and soaring inflation despite Washington lifting an economic embargo in October 2017.
Inflation is running at 70 percent and the Sudanese pound has plunged in value, while shortages of bread and fuel have regularly hit several cities.