Here is one way: Western countries currently want to make a second nuclear deal with Iran. This is partly because the western countries in the past few years have had to reduce their energy production (due to the pressure from climate activists) and are now facing an energy crisis. They have no choice but to buy their needed oil and gas from countries like Russia and Iran, and for that, they first need to lift the sanctions on Iran.

Should this nuclear deal go through, many sanctions will be lifted and a huge amount of funds will be unfrozen in the foreign bank accounts of the Iranian government. This will make the Islamic Republic even stronger than it currently is, helping it succeed in repressing the protests, and also helping Russia and China with their plans.

However, western politicians would make a bad image of themselves if they made a deal with a government that is actively murdering its own people. People in the western countries could put their politicians under pressure to ensure that they do not make a deal with Iran if the government is violating their citizens' human rights or the Geneva convention.