Israel has intercepted nearly two dozen ships in the Global Sumud Flotilla bound for Gaza and detained at least 200 people, according to the convoy’s organizers, including Swedish climate activist Greta Thunberg.

The Israeli navy on Wednesday intercepted an aid flotilla bound for Gaza that was being closely watched around the world through their social media posts, according to activists within the flotilla.

The Global Sumud Flotilla, which consists of more than 40 civilian boats carrying about 500 parliamentarians, lawyers and activists including Swedish climate campaigner Greta Thunberg, is trying to b...