The First Lady tweeted 3 pics Saturday showing her, her team and a group of construction crew members wearing hard hats and checking blueprint plans for a new tennis pavilion she's having installed at the White House -- which is being funded by private donors.

Of the project, she wrote ... "I am excited to share the progress of the Tennis Pavillion at @WhiteHouse. Thank you to the talented team for their hard work and dedication."

Innocent enough, right? WRONG!!!!!!!  Or so says a bunch of Twitter users who immediately flooded her timeline with accusations of being tone-deaf, out of touch and super-snobbish to put a spotlight on a somewhat frivolous effort while a global pandemic is unfolding.

You can go check the comments for yourself, but yeah ... people weren't happy with this. Lucky for them, MT heard 'em loud and clear -- and responded accordingly.

She fired back with a relatively subtle jab ... "I encourage everyone who chooses to be negative & question my work at the @WhiteHouse to take time and contribute something good & productive in their own communities. #BeBest." Taking the high road, it seems.

Part of the reason Melania's catching flak here is because she's been pretty quiet about the coronavirus, not to mention the destructive tornadoes in Nashville last week.

By the same token, this isn't nearly as bad as her "I Don't Really Care" moment. And just for a little context ... Barack Obama did some work on the WH tennis court back in '09 to turn it into a full basketball court. Right in the middle of the swine flu pandemic, too.