"Stay well behind confrontation lines and ensure that you have adequate protective equipment for all eventualities," a warning from the International News Safety Institute said. "Consider bringing a flak jacket and a gas mask."
A Ukrainian decision in November to protect its economic ties to Russia instead of moving closer to the European Union sparked massive demonstrations in Kiev. Protests turned violent this month when the Ukrainian government endorsed legislation to curb protests, a measure since repealed.
INSI, which has headquarters in London, said police and demonstrators have used violence in recent weeks.
Catherine Ashton, the top foreign policy official for the European Union, said she that despite conflicts between ruling and opposition leaders in Kiev, one of the most unnerving aspects to the situation was the level of violence.
"Wherever it comes from, the sense of violence and intimidation, it must stop," she said in a statement Wednesday.
On Thursday, the Parliamentary Assembly of the Council of Europe censured Ukraine for the November decision.