Barack Obama, being a typical liberal, can't stay out of other people's affairs. Or other countries' matters for that matter. So of course our busy-body president had to weigh in on the British vote in regards to staying in the European Union, and Obama the internationalist, who despises local government because it's a check on the power of national government, and he hates national governments when they don't follow his leftist directives. He can always try to fall back on the United Nations when Congress doesn't do his bidding on issues such as global warming.
Obama was opposed to what was dubbed "Brexit," that is, Great Britain leaving the EU.