I cashed in I and EE bonds & used the funds to pay off my student loans. Is there a credit for the interest earned on these because I paid off my loans with the funds?

No, the Savings Bond Interest Exclusion (IRS Form 8815) only allows you to exclude the tax on interest if it is used for "tuition and fees". Loan payments don't qualify.

you may be able to deduct the interest expense on your student loans. ‌See What is a 1098-E: Student Loan Interest for more information. 

There's a "loop hole" to pay down student loans with US savings bonds and get to exclude the interest from taxation.

Contributions to a 529 plan are a qualified educational expense for the savings bond interest exclusion. It's call a rollover and must be done within 60 days of cashing the bonds. 

After doing that, you can pay down the student loans with a distribution from the 529 plan.  Student loan payments (up to $10,000 lifetime maximum) is a qualified expense for a 529 distribution. 

But directly paying loans with cashed bonds is not qualified.