Is it obligatory to participate in a specific demonstration organized to achieve one of the Muslims' demands, such as removing oppression?

Demonstrations are a permissible means, with certain controls, and are not prohibited in themselves. The absolute statement that participation in them is obligatory is groundless, for enjoining good and forbidding evil is a collective obligation (fard kifaya), not an individual one (wajib 'ayni), except in specific circumstances. The permissibility of demonstrations is a matter of disagreement among contemporary scholars, and they vary in their causes, effects, and harms. Therefore, it is not correct to issue a general ruling on them other than their permissibility in principle.