Sunday's attack on Doctors Without Borders' medical facility killed four people and wounded 10 others.
"[We] strongly condemn this and we reiterate to all parties to the conflict that patients & medical facilities must be respected," a spokesperson for Doctors Without Borders told Reuters
A similar incident occurred last month, when nine people were wounded at another medical facility run by the NGO in Taiz, southern Yemen.
The situation in Yemen has escalated since last March, when the country entered a state of full blown civil war.
Recently the Saudi-led coalition's bombing of Houthi rebels.
However it has not been confirmed whether the strike on the facility was made by the Saudi-led coalition or by a rocket fired from the ground.
The latest talks between the government and rebels, which took place in Switzerland last month, failed to reach a breakthrough.
According to AFP, the UN envoy for Yemen Ismail Ould Cheikh Ahmed arrived Sunday in Sanaa in a bid to convince the rebels and their allies to attend fresh peace talks slated for next week.
But Foreign Minister Abdel Malak al-Mekhlafi told AFP Saturday that the talks will not take place until 20 January at the earliest.
More than 5,800 people have been killed in Yemen since March - about half of them civilians - according to the United Nations.