It's possible.  In some states, probation conditions are worded so that it is the arrest, not (just) the conviction, that violates your probation.  The other question that might be asked is why the new charges were dismissed.  If it was discovered that you had nothing to do with the crime, that would probably help you avoid a probation violation.  However, if the dismissal was for insufficient evidence, that doesn't always mean the probation department has to ignore the arrest.