Plugins won't load...

Okay so I just made a fresh bukkit server with the bukkit server.jar and all that. My Bukkit server works fine without plugins. I run it in terminal (I'm a mac user) and it loads the whole world correctly and I can connect to it no problem. However, when I try to put in a plugin (for example, in this case I will use MorePlugins.jar) it doesn't work. I put the MorePlugins.jar into the plugins folder, and this is what happens:
21:46:26 [INFO] Starting minecraft server version 1.6.4
21:46:26 [INFO] Loading properties
21:46:26 [INFO] Default game type: SURVIVAL
21:46:26 [INFO] Generating keypair
21:46:26 [INFO] Starting Minecraft server on (hidden (hopefully))
21:46:26 [INFO] This server is running CraftBukkit version git-Bukkit-1.6.4-R2.0-b2918jnks (MC: 1.6.4) (Implementing API version 1.6.4-R2.0)
21:46:26 [SEVERE] Could not load 'plugins/MoreSpawns.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.UnsupportedClassVersionError: com/dorkrepublic/morespawns/MoreSpawns : Unsupported major.minor version 51.0
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:184)
at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305)
at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
at org.bukkit.craftbukkit.v1_6_R3.CraftServer.loadPlugins(CraftServer.java:241)
at org.bukkit.craftbukkit.v1_6_R3.CraftServer.<init>(CraftServer.java:219)
at net.minecraft.server.v1_6_R3.PlayerList.<init>(PlayerList.java:56)
at net.minecraft.server.v1_6_R3.DedicatedPlayerList.<init>(SourceFile:11)
at net.minecraft.server.v1_6_R3.DedicatedServer.init(DedicatedServer.java:107)
at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:393)
at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
Caused by: java.lang.UnsupportedClassVersionError: com/dorkrepublic/morespawns/MoreSpawns : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:637)
at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:80)
at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:249)
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:173)
... 9 more
21:46:26 [INFO] Preparing level "world"
21:46:27 [INFO] Preparing start region for level 0 (Seed: -2097320105270876930)
21:46:27 [INFO] Preparing start region for level 1 (Seed: -2097320105270876930)
21:46:28 [INFO] Preparing start region for level 2 (Seed: -2097320105270876930)
21:46:28 [INFO] Server permissions file permissions.yml is empty, ignoring it
21:46:28 [INFO] Done (2.006s)! For help, type "help" or "?"

Can anyone please help me out? Thanks in advance!

 

The plugins are compiled against a later java than your JRE.
Also wrong section.

 

Raindomize

Thread moved to the appropriate subforum!

Also, you need Java 7 to run that plugin