Donald Trump NBC Needs to Worry ... About 'Lying' Brian Williams

7/11/2015 8:14 AM PDT

Donald Trump must be fed up with getting bashed in the media ... because he lashed out with a pot shot of his own ... at his ex-biz partner NBC, and its embattled news anchor Brian Williams.

Trump fielded a lot of questions about his Mexican immigrants comments during a Friday news conference in L.A. -- but really went off when the subject of NBC dumping him came up ... Trump went for the jugular.

Check out the video ... we doubt the Donald and Williams will be sitting down for a campaign trail one-on-one after this.

We also asked Trump if proud Republican Caitlyn Jenner would have a role at the party's convention -- interesting response.