There is no direct equivalent to provisional patent app. in Europe (ie the EPO). However, you can establish a priority date by filing a normal national or European (or PCT) patent application and don't pay any fees. This gives you an established priority date for the filed subject matter and under the given applicant's name (only YOU can claim this priority and no one else). You can now use this patent application number to claim priority strictly within 12 months and file a normal european (or PCT) patent application, i.e. pay all fees etc. Another trick here is that only the first application may give a valid priority right. So if you have already filed the US provisional, you can't file another patent application and claim prio from that one. BUT you CAN claim priority for filing a normal EP (or PCT) application by the US provisional. The danger here lies in the fact that US provisionals may well be only experimentals and that will give you limited subject matter to claim priority from in EPO proceedings. But if it is drafted like a normal patent application you will be fine.
I should strongly advice to consult an EQE qualified EPO patent attorney, because many US applicants have lost their patents for not being aware of the strict regulations about claiming priority. The most recent and painful example is the revocation of one of the CRISPR patents of the Broad Institute (see here for some reading http://ipkitten.blogspot.gr/2018/01/epo-revokes-crispr-patent-clear-cut.html). They will probably lose more of them on the same basis and it is really a shame to lose a patent for invalidly claiming priority.