The right to peaceful assembly and protest are fundamental principles of any democracy. The UK Government must call on Cuba's Government to respect the civil right of its citizens to peacefully protest.
You may be interested in these active petitions
Non-violent protests are a fundamental right to democratic societies and have been throughout history. It is how policies have been challenged and changed in the past. Without them, you are effectively saying nobody has the right to peacefully challenge anything. If people feel the need to protest a government should listen and not shut down this legitimate way of people voicing their concerns and opinions.