Our architect has solved this issue with the help of creator of Glass library. And the solution is like this..
[SitecoreField]
public virtual IEnumerable<MediaImage> Images { get; set;}
And Media Image is class like:
[SitecoreClass]
public class MediaImage
{
[SitecoreField("Attachment")]
public virtual Stream Image { get; set; }
[SitecoreInfo(SitecoreInfoType.MediaUrl)]
public virtual string Url { get; set; }
[SitecoreField("Alt")]
public virtual string Alt { get; set; }
}
This has solved the issue and I am getting the list of images now.