it is not that ...; it doesn't mean that ...
Used to deny a possible interpretation or to clarify that something is not necessarily the case. Often follows a clause in plain form. It is usually written in kana.
See also: 訳 (わけ)
Just because he isn't coming doesn't mean he dislikes you.
毎日勉強しているわけではないが、テスト前には集中する。
It's not that I study every day, but I focus before exams.