The clot risk was "low", said a European Medicines Agency (EMA) ruling on a French-initiated review of the drug's safety.
But it stressed Diane-35 and its generics should only be used when alternative acne treatments had failed and said measures must be taken to minimise the blood clot risk.
"These medicines should be used solely in the treatment of moderate to severe acne... in women of reproductive age," the agency said in a statement.
"Since Diane-35 and its generics are hormonal contraceptives, women should not take these medicines in combination with other hormonal contraceptives."
Produced by German drugmaker Bayer, Diane-35 is authorised in over 100 countries and is used by millions of women.
In January, French health regulator ANSM launched a probe into the drug which it linked to four deaths due to thrombosis in the past 25 years.
In France, Diane-35 is authorised only for acne treatment, but its hormone make-up means the drug also works as a contraceptive by blocking ovulation.