Creating a tar.gz archive with Maven

I have a Maven project, where under src/main directory there is a sub dir called output. this folder needs to be packaged into tar.gz. when using the assembly plugin as follows:

From the pom.xml:

<build>
<finalName>front</finalName>
<plugins>
    <plugin>
    <artifactId>maven-assembly-plugin</artifactId>
    <version>2.2-beta-5</version>
    <configuration>
      <descriptors>
        <descriptor>src/main/assembly/assembly.xml</descriptor>
      </descriptors>
    </configuration>
  </plugin>
  </plugins>
</build>

the assembly.xml:

<assembly>
    <id>bundle</id> 
    <formats>
        <format>tar.gz</format>
    </formats>
    <fileSets>
        <fileSet>
            <directory>src/main/output</directory>
        </fileSet>
</fileSets>
</assembly>

My problem is that I am trying the outcome will be as running the tar utility itself, meaning when extracting to get output directory and all its content. what I get is the output folder wrapped with all the project path - name/src/main/output.