Armed men stormed the building housing the Libyan Foreign Ministry, calling for a moratorium on the hiring of officials from the regime of Moammar Gadhafi, who died during the 2011 civil war.
Libyan security has lapsed in the wake of the war. The French Embassy in Tripoli was bombed last week and foreign governments have warned of the security risks in most major metropolitan areas of the country.
The U.N. Security Council issued a statement saying attacks on diplomatic interests could "seriously impede" the work of the international community in Libya.
An attack on the U.S. consulate in Benghazi, Libya, last year resulted in the death of U.S. Ambassador Chris Stevens and three members of his staff.
Zeidan said Tuesday that Libyans should rally around the central government, which is struggling against "people who want to destabilize the country," the BBC reports.
The BBC reports that about 20 vehicles carrying men armed with assault rifles blocked most of the major roads leading to Tripoli. The BBC reports the militia is unorganized, however.