The Pump Family tells TMZ ... "It's with heavy hearts that we announce that the lease at Pump Restaurant is expiring, and we will be closing its doors on July 5th, after 10 years of beautiful evenings under our olive trees."

While the flagship location at the corner of Santa Monica and Robertson in the heart of WeHo is closing, we're told Lisa is opening two more restaurants at Caesars in Las Vegas.

It appears a dramatic increase in rent is to blame, the Pump Family tells us ... "While we have loved our time operating Pump, to take on another 10-year lease with a huge increase in rent by the landlords, is not something we are ready to commit to. After successfully running 37+ establishments for many years, this type of rent is untenable."

Sources close to the family tell TMZ  … Lisa and her husband Ken Todd refused to commit to paying nearly $1 million in yearly rent, with the couple considering the figure to be ridiculous.

Our sources say high rent is also to blame for Lisa and Ken's former Beverly Hills restaurant, Villa Blanca remaining empty 3 years after the couple closed the restaurant because of a rent increase in 2020.

We're told Lisa wanted to keep Pump open through June, because it's Pride Month and she wants to "support the local community with one last hurrah."

Lisa and Ken still have a couple other restaurants in the area ... Sur and TomTom ... and the Pump Family says, "We look forward to welcoming you all to TomTom & Sur in the months following! Thank you for the past decade of support, we have loved our staff, our patrons and our time together."

Pump's been featured in many scenes on "Vanderpump Rules" over the years, and it's hosted tons of celebs ... including Lance Bass and Lady Gaga.