I have the same issue:
$ docker run hello-world Unable to find image 'hello-world:latest' locally Pulling repository docker.io/library/hello-world docker: Network timed out while trying to connect to https://index.docker.io/v1/repositories/library/hello-world/images. You may want to check your internet connection or if you are behind a proxy.. See 'docker run --help'.
Diagnostics:
Docker for Mac: version: mac-v1.12.0-beta16.2
OS X: version 10.11.4 (build: 15E65)
logs: /tmp/20160628-102126.tar.gz
failure: No error was detected
[OK] docker-cli
[OK] app
[OK] menubar
[OK] virtualization
[OK] system
[OK] osxfs
[OK] db
[OK] slirp
[OK] moby-console
[OK] logs
[OK] vmnetd
[OK] env
[OK] moby
[OK] driver.amd64-linux