There's no extradition treaty between the US and Russia. The state department FAQ says,
Where can I find a list of countries with which the United States has
You may find a list of these countries at 18 U.S.C. § 3181.
The link is to http://www.state.gov/documents/organization/71600.pdf, which makes no mention of Russia. So if you're prepared to accept the US Government's word for it, Russia is not a country with which the US has an extradition treaty.
Anyway I don't believe that what you quote actually contains a claim by Obama that Russia is not abiding by international law. It certainly doesn't specify what the legal nature of the breach might be, if there is a breach involved either in "talking about potentially offering Snowden asylum", or in actually offering it. It doesn't claim that Russia would be required to extradite.
What it says is, that Russia should abide by international law. Or, literally, it just says that it is expected that they will recognise that they should abide. This "claim" is of course true as far as it goes, which isn't far.