Dozens were wounded in clashes with Yemeni security forces inside and around the embassy during a mass demonstration over a controversial American film that allegedly denigrates the Prophet.
"The main building of the US embassy is still well protected with Yemeni and US security forces but some protesters managed to climbed into the external walls of the embassy," a security official of the Yemeni interior ministry told Xinhua.
"The situation now is under control and the roads leading to the embassy were blocked," he said on condition of anonymity.
However, witnesses said more reinforcement of the Yemeni security forces were sent to the embassy as more protesters managed to breach the security blockades.
"You Americans, stop insulting our Prophet!" chanted dozens of people at the gate of the US embassy.
It was not clear if there were any injuries among the US diplomatic staff or whether they were evacuated.
Protesters set fire to a number of diplomatic vehicles as well as part of the building, as security forces used water cannons and warning shots in a bid to drive them out.