I can't register for the tournament

I want to register for 1300 blitz there is no button to enter the tournament although my rating is 1293 at the moment

which tournament?

IIRC the requirement usually is that your rating has to be within the limit for the last week.

You may search the forum - this answer has been discussed numerous times.
I remember something like, if you already went over 1300, then you can't attend a tourney below 1300 for about 1 week or so...

Have fun!