A drone strike has killed three suspected Al-Qaeda militants in Yemen after Washington vowed to continue its campaign against the jihadist group despite the country's ongoing political crisis.

US President Barack Obama on Sunday insisted Washington would pursue its efforts against Al-Qaeda in Yemen regardless of upheaval that has seen Western-backed President Abdrabuh Mansur Hadi tender his resignation.

The unrest continued on Monday with the Shi'ite militiamen, known as Huthis, attacking protesters gathered at the university in Sanaa to demonstrate against their continued occupation of the capital.

Monday's drone strike saw an unmanned aircraft, which only the United States operates in the region, fire four missiles at a vehicle in a desert area east of Sanaa, killing three suspected Al-Qaeda militants, a tribal source told AFP.

Yemeni authorities have for years allowed Washington to carry out strikes against Al-Qaeda in the Arabian Peninsula (AQAP), the local branch of the jihadist network which claimed responsibility for this month's deadly attack on French satirical weekly Charlie Hebdo.

In India on Sunday, Obama had vowed the United States would "continue to go after high-value targets inside of Yemen".

Hadi resigned last week after the Huthis kidnapped his chief of staff and seized key buildings across the capital.

The unrest has raised fears of strategically important Yemen, which lies next to oil-rich Saudi Arabia and along key shipping routes, collapsing into a failed state.

On Monday Huthis armed with daggers attacked protesters who gathered inside the campus of Sanaa University to demonstrate against them, leaving 10 people wounded, activists said.

The Huthis had earlier blocked access to the university and the nearby Change Square with road barriers in a bid to prevent demonstrations.