"I ask the immediate cessation of the hostilities in and around the crash site by both Ukraine and separatist forces," he said after talks with his Dutch counterpart Mark Rutte in The Hague.
"We ask that all sides respect the lives lost and the integrity of the site. The long walk towards justice begins with this step."
Rutte said crash investigators and those charged with retrieving bodies may not be able to access the site for days.
Malaysia and the Netherlands shared three priorities, Rutte added: to bring home the victims' remains and belongings, determining the cause of the disaster and ensuring the perpetrators are brought to justice.
"We will have to seriously take into account the possibility that we will not be able to gain access (to the crash site) in the coming days either," Rutte said.
Dutch and Australian investigators have been thwarted in their efforts to reach the site for five day in a row by fighting on and around the route there from Donetsk.
Kiev today announced a day-long halt to its deadly offensive to oust pro-Russian rebels in east Ukraine in an effort to allow the investigators to access the site.
UN Secretary-General Ban Ki-moon has also called for a halt to fighting in the area of the crash, where remains from some of the 298 victims lie festering in the sun some two weeks after the jet was shot down over rebel territory.
