There is probably a lot of really interesting politicking going on behind closed doors with all the Arab Spring unrest, much of it sensitive enough that it's not going to be adequately visible to reliably report on it. We have good reason to believe that the US (through the CIA) and the UK (likely through MI6) are providing covert aid to the rebel forces, who are also receiving aid from various international Islamic militant groups including AlQ. Balancing these groups (or perhaps remaining uneasy cooperation) could resemble Scylla and Charybdis from the Free Syrian Army, which presumably wants any democratic Syria they would build to be reasonably independent from both. Likewise, Russia (which has moderate economic ties to Syria and a general disinterest in seeing fake democracies challenged) and Iran (which would not like to see the Shia minority that rules the country removed from power and is also likely worried that any new order would be closer to Washington than the present one) are supporting Syria in various ways but need to hedge their bets in case the Assad dictatorship survives. Iran has more to lose if the current political order shifts, and has sent snipers to aid the regime.
AlQ and internationalist MB members, recently having seen the elections in Libya not follow Egypt in putting Islamism (either extreme or moderate) might reasonably be wondering whether getting heavily involved in this revolution is worth it, and for similar reasons the west might be concerned.