The WHO said the attacks increase the risk of disease spread and are "profoundly disrespectful."
The attack is the second to target MSF treatment centers in just a matter of days.
The shuttered MSF center has admitted more than 600 people since December, 49 with confirmed infections.
Thirteen new cases raise the outbreak total to 872 cases, including 548 fatal ones.
The Saudi Arabian Ministry of Health (MOH) announced seven new cases of MERS-CoV over the weekend, recorded in reports for epidemiologic weeks 8 and 9. Three of the cases are in Wadi ad-Dawasir, two of which appear to be part of an ongoing hospital outbreak.
The new Beni case is among 6 reported today, bringing the outbreak total to 859 cases.
Officials halted surveillance activities in Vuhovi after a nurse from Bisongo was killed.
Also, 3 new cases raise the outbreak total to 848, including 529 deaths.
The DRC warned, however, that travel between Beni and other affected areas could bring the virus back.
The country's health ministry reports 6 new cases and 5 new deaths, including that of an infant.
