The closest English phrase I can think of is "I'm rooting for you." ...
· Comment — Shoshannah Tekofsky's post · View on Facebook · Markdown source
The closest English phrase I can think of is "I'm rooting for you." However, it doesn't necessarily imply you'll take action on their behalf. You could also say "I've got your back." or "I'm right behind you.", which imply greater willingness to act.