Yemen's exiled government pulled out of the talks on Sunday as troops from the Saudi-led coalition that is seeking to restore it took part in ground fighting in a central province for the first time.
Saudi soldiers died "in the line of duty while protecting the nation's borders".
Cameron's visit comes amid the flow of tens of thousands of Syrian refugees to Europe.
A joint police and military operation on Sunday "chasing terrorist elements" in Wahat "mistakenly" targeted four pick-up trucks carrying Mexican tourists, the interior ministry said in a statement.
Palestinian President Mahmoud Abbas condemned what he called an Israeli police "attack" at the site, while Israeli Prime Minister Benjamin Netanyahu said authorities must prevent rioting at the compound.
Indian officials in Makkah are continuing to provide assistance to the 19 injured Indian pilgrims, said Ministry spokesperson Vikas Swarup.
The deaths came in clashes that began on Tuesday when two prominent rebel groups launched simultaneous attacks on three areas outside the capital.
Sikandar, a sailor, sent an audio message in which he said that they last night came under a bomb attack.