Protesters chanted slogans demanding the ouster of President Ali Abdullah Saleh, in power for 32 years, the AFP correspondent said.
Around 100 of Saleh's supporters held a pro-government protest across the street from the campus while police set up a cordon to separate the two groups.
Pro- and anti-Saleh demonstrators have clashed violently over the past week in Sanaa with guns, batons and rocks with anti-regime protesters calling on the president -- who has been in power for 32 years -- to quit.
On Saturday, the police did not intervene as fierce clashes left five students wounded, according to an AFP correspondent.
Protests have become increasingly violent in poverty-striken Yemen despite calls by Saleh -- who was elected to a seven-year-term in September 2006 -- urging dialogue to form a government of national unity.
Anti-government demonstrations have also taken place in the southern regional capital Aden and several people have been killed by police there.
On Sunday the police arrested the main southern opposition leader, Hassan Baoum, shortly after he arrived in Aden to take part in an anti-government protest, his son said.
Baoum was arrested along with his son Fawaz at the Naqib hospital after he had undergone some medical tests, another son said.
He said that Baoum arrived in the port city from nearby Lahij earlier in the day with the intention of joining the protest.
Police have killed 10 people in Aden in the past week, according to an AFP tally, as they resorted to gunfire to disperse frequent protests against the government of President Ali Abdullah Saleh.
Baoum had only come out of custody earlier this year after a previous arrest on November 9.
Baoum heads the supreme council of the Southern Movement, the main organiser of protests in the south in recent months. The movement's members want either secession or increased autonomy for the formerly independent region.
Residents complain of discrimination by the Sanaa government in the distribution of resources since union between north and south in 1990.
The south broke away again in 1994, sparking a brief civil war that ended with the region overrun by northern troops.