MSF`s head of mission warned that the bombing of civilians and hospitals was a violation of humanitarian law.
There has so far been no comment from the coalition, which is battling the Houthi rebel movement.
Air strikes and fighting on the ground in Yemen have killed more than 5,700 people, almost half of them civilians, since the coalition began a military campaign to restore the country`s government in late March, according to the UN.
The already dire humanitarian situation has also deteriorated severely, with more than 21 million people - four-fifths of the population - now requiring aid.
Hospitals overwhelmed
Yemeni pro-government forces, backed by coalition aircraft and ground troops, have been fighting the Houthis and their allies for control of Taiz for months.
MSF said two of its staff were among those wounded when its tented clinic in the southern city`s al-Houban district was hit on Wednesday morning.
The coalition had been informed about the facility`s precise location and the activities carried out by MSF in al-Houban, most recently on Sunday, it added.
"There is no way that the Saudi-led coalition could have been unaware of the presence of MSF activities in this location," said Jerome Alin, MSF`s head of mission in Yemen.
"The bombing of civilians and hospitals is a violation of international humanitarian law," he added. "Civilians seeking healthcare and medical facilities must be respected."
Last week, the UN`s aid chief warned that those hospitals still functioning in Taiz were overwhelmed with wounded patients and faced severe shortages of doctors and nurses, medicines and fuel.
In a separate development on Wednesday, militants from al-Qaeda in the Arabian Peninsula (AQAP) reportedly overran two towns in southern Yemen.
Residents said the jihadists raided Jaar and killed the deputy commander of pro-government popular committee militias in the town. Most of them later withdrew to Zinjibar, to the south, the residents added.
Jaar and Zinjibar are about 50km (30 miles) east of the port city of Aden, home to the government`s headquarters. The Houthis control the capital, Sanaa.
In April, AQAP militants took advantage of the instability in Yemen and seized control of Yemen`s fifth largest city, Mukalla, which is further east of Aden.
