Pupils will now only be authorised to miss school to go on climate strikes once a year after a decision by Edinburgh City Council.
Activists have vowed to "keep challenging" the limitation after a meeting of the local authority 's education committee on Friday.
Pupils had previously been turning up to protest outside the Scottish Parliament on an "ad hoc" basis, with permission first granted by the council in March.
It was the first local authority in Scotland to make such a move.
Now, absences to protest that are not part of the agreed day off during the academic year will be recorded as unauthorised, with "parental consent" required.
Eight councillors voted for the motion, while two - both Greens - voted against.
More action is planned by the Scottish Youth Climate Strike (SYCS) group on September 20 and 27 as part of what has become a continuing global movement started by 16-year-old Greta Thunberg.
Sandy Boyd, of SYCS, told the PA news agency after the meeting: "It's a little disappointing, but they have given us permission for one strike a year.
"We will keep striking no matter what and we will keep challenging the council on this."
Thousands of children previously descended on the Scottish Parliament building in March and May along with fellow pupils in more than 100 towns and cities across the UK.
Smaller groups have been gathering at Holyrood every Friday since January
Edinburgh City Council education convener Ian Perry said: "We support the young people making their voices heard regarding climate change as it is one of the most important issues that's facing the world.
"However, there needs to be a balance struck and if we allow pupils more than one absence the issue is that they could be regularly missing school which affects their education.
"We are also encouraging schools to support pupils in any projects which help educate them in school about climate change."
