No one was every caught or even identified after the Dubai murders, so associating this with Mossad is pretty preliminary at best.
Most strange, is that two of the assassins left Dubai on flights to Iran. Iran is suspicious of all foreigners, particularly ones from western countries. Iran imprisons foreign hikers on their borders for months. But for some reason two western foreigners coming on a flight from Dubai just disappeared, and Iran's has no idea where they went. Normally, the capture of foreign spies would be cause for a huge media campaign.
And while Mossad is often spoken of as being the ultimate murdering bad asses, most people forget that Mossad supplied F16 parts to Iran during the Iran-Iraq war. So while the current gov't leaders in Iran might get a lot of lift in the polls with their anti-Isreal rhetoric, the reality is that the Mossad has an understanding with the Iranian military.
So the Mossad may have killed this guy, but Iran probably sanctioned it. Iran has a big probably with terrorism as well, and perhaps this guy was supplying weapons or explosives to them as well.