'Dallas' Star Victoria Principal's Home Compromised by Trespassers -

Victoria Principal's private home became an unwanted open house this week -- courtesy of a couple of alleged trespassers who claimed they saw the place was for sale online and were told they could take a tour ... this according to law enforcement.

Cops say officers were called to the "Dallas" star's Malibu property Monday after a man and woman were spotted by security on surveillance cameras breaking through a gate and wandering onto the grounds.

Our sources say Principal's security lost sight of the pair, which made them think they might've broken into the home -- so we're told the call was upgraded to a possible burglary.

When cops arrived, they found the couple ... and cops say their explanation to officers was that they thought the crib was for sale -- claiming they'd seen an ad for it online and thought they'd pay the place a visit in person for a closer look.

We're told they even showed cops something they said was proof of a conversation between the couple and an unknown person on Craigslist trying to sell the home ... even giving instructions on how to get in.

Gallery Launch Gallery Victoria Principal Through The Years Launch Gallery Getty

Principal -- who wasn't home -- was contacted ... and our sources say she denied the house was for sale and insisted the couple had no business being there. We're told only one of them ended up being cited for vandalism ... and that they were released without incident.