Can a priest, as a matter of personal conscience, refuse to marry a Catholic with a non-Catholic?

The Catholic Church does give dispensations for Catholics to marry members of other Christian churches or other religions. A priest may refuse to witness a marriage because he judges one or both parties to be too young or lacking in sufficient psychological maturity, etc. Further, the priest may refuse to officiate, but he cannot prevent the couple from going to another priest who might have a different pastoral opinion. All things being equal, Catholics have a right to the sacraments.