The cost of a gallon of gas dropped below $3 a gallon here in Houston! I just filled up for $2.96 a gallon...saved almost $10 on a tank of gas! HOORAY FOR PRESIDENT OBAMA! His mastery of foreign policy helped to bring about big savings at the pump for the average American!
In an indirect way the US policy of peace in the ME has a lot to do with gas prices. It has encouraged stability in the markets. In the long run, is that due to Obama's policies such as his winning policy for Syria and the prospects of him finding a solution for the US's problem with Iran becoming nuclear capable and immune to US aggression. Yes, most likely Obama should be given some credit
Generally on any specific day the President does not have much to do with the price of gas. Overall policy, over a matter of years may affect, somewhat, the price of gas.
In general the price of gas is set by what the economists at the oil companies believe they can get away with at any given time.