A statement from the US embassy here said it was greatly concerned by reports of attacks on students in Jaffna.
"We call upon authorities to exercise restraint and respect peaceful demonstrations," it said.
Students had clashed with police in Jaffna yesterday after the university was searched for LTTE material following reports that students were planning to celebrate 'heroes week', which was commemorated by the LTTE in the last week of November to commemorate fallen cadres.
Around 20 students were injured in the clash as they protested a military search at the University premises in the former LTTE stronghold.
Authorities said the students planned to stage an illegal march.
The US embassy also expressed concern about reports of threats to freedom of expression in Sri Lanka.
"The November 28 beating of a reporter in Jaffna, harassment by Government of Sri Lanka officials of independent media outlets, and searches without warrants of journalists all serve to stifle media freedom," it said.
