Donald Trump's old golfing buddy, George Lopez, is not down with POTUS' new, $50k golf simulator at the White House ... telling TMZ Sports the guy should be focusing on his job, not his stroke.
ICYMI -- The Donald recently had a room-sized golf simulator installed in the personal quarters at 1600 Penn ... and it's reportedly a big upgrade from what Barack Obama had during his presidency.
G Lo -- who has hit the links with Trump prior to becoming #45 -- tells us the move is "unnecessary" .