This isn't quite true.
Iran goaded the US into invading Iraq, perhaps supplying the fake evidence used to link Saddam Hussein to WMDs. This was at least Hussein's opinion, and why he did not take US threats immediately leading up to the war seriously. Saddam's successor, Chalabi, was an Iranian agent [[1].
Bashar Al-Assad aggressively sponsored terrorism and sectarian violence in Iraq. In the early days, most fighters from Iraq were from Syria, or came through Syria. It was not without irony that the conflict later spilled over into his country.
The leaders of the Middle East are not without fault, they clumsily used the West's domestic insecurities (and Russia's) for their own military gain. In Syria they unleashed forces they could no longer control.
[1] http://www.nytimes.com/2012/01/26/world/middleeast/26iht-m26...