Such protests are rare in Sudan but anger has been rising over high food prices and government plans to cut fuel subsidies to plug a ballooning deficit - a move that would hit the poor. Inflation is running at 30 percent.
Around 200 students staged a protest at noon outside the main university campus in the centre of the capital shouting "The people want lower prices" and "The people want to overthrow the regime," witnesses said.
Riot police fired tear gas and used batons when the crowd tried to spread out on the main street outside the campus, they said. Some students threw stones at the police.
The police were not immediately available to comment.
A Reuters reporter who arrived after the protest ended saw police and security agents armed with iron rods detaining some students and driving them away in trucks. There was a heavy security presence all over the city centre.
Sudan has been in economic crisis since it lost three-quarters of its oil production - its main source of state income and hard currency - when South Sudan became independent a year ago. The government wants to remove fuel subsidies to plug a $2.4 billion deficit.
Khartoum and other cities have seen some small protests against rising inflation recently, but opposition parties have failed to capitalise on them. Authorities temporarily closed Khartoum University in December after more than a week of protests against the government.
President Omar Hassan al-Bashir will address parliament on Monday morning, the state news agency SUNA said late on Saturday.
It gave no details but a diplomat said Bashir was likely to announce details of the fuel subsidies and austerity measures.