Pull request permission vs merge pull request permission

Hi, i would like that only a couple of person on the team can accept and thus merge pull request. If i set those person in the "Merge via pull request" under "Branch permission", all the other developer will have a "permission denied" when trying to create a pull request.

Pull request is created by SourceTree; if i grant "Merge via pull request" permission to the user, then he can create (and accept) the pull request.