Allocate maximum memory to your docker machine from (docker preference -> advance )
Screenshot of advance settings:
This will set the maximum limit docker consume while running containers. Now run your image in new container with -m=4g flag for 4 gigs ram or more. e.g.
docker run -m=4g {imageID}
Remember to apply the ram limit increase changes. Restart the docker and double check that ram limit did increased. This can be one of the factor you not see the ram limit increase in docker containers.