Thanks for your answer. Your solution worked for me. However, I was expecting an easy solution using buttons to do that (like for commits, pull and push). In my company many people like to work with RStudio but they are not familiar with terminal commands... That's why I was asking.
Yeah I know. Personnaly, I also use another GUI tool specific to GIT called GitExtension (I am on Windows). It is very complete and you can do everything you can do with git with click-button. I advice every newcomer to git to use it in my company until they are at ease with git.
I don't know what's new about Git integration in future version of Rstudio. Maybe someone from RStudio team will chime in to give us some infos !