Java with RWeka packege

I have mac EL Capitan, 10.11.5, I used RWeka package, it downloaded correctly and initialized with any error, but when I apply

J48(Species ~ ., data = iris)

I have this error

Error in .jnew("weka/core/Attribute", attname[i], .jcast(levels, "java/util/List")) : 
  java.lang.UnsupportedClassVersionError: weka/core/Attribute : Unsupported major.minor version 51.0

I used java version with these details,

52F85:~ kameljabreen$ java -version
java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)

Please help me to solve this problems, it is my problm since one month, I read a lot about this problem in web sites. I did all thing, installing java JDK version 1.8 .... ect. now I used java 1.7. Please give me solutions. Thanks in advance