It probably knocked a connector and caused a fault.
The fault will probably be "high impedance in air bag system" or something like that.
There is really nothing to fix, just get the light turned off and don't hit any more potholes.
You have seat side air bags then.
These are a weak point in the car.
I would personally swap the connectors for something better.
Even if the airbag didn't deploy, in a half decent crash the seat belt pretensioners will fire.
This locks the seat belts and turns on the airbag light. You will need new seat belts and the error codes deleting.
You may have knocked the side boot trim and affected the connections to the seat belts.
Things can just break and connections can just become faulty.
If you have seat side airbags, you will have side impact sensors behind the seat on the side wall under the carpet.
Disconnect and clean all connections relating to the airbags, sensors and seatbelts. Clean the connections a
nd connect them all back up again. You will then need to delete the error code to see if it worked.
No amount of fixing and disconnecting batteries will turn the light off.
You need to visit smart or a smart specialist to have them erase the error code.
Unless you have one of the few code readers that will delete the airbag codes.