Hillary Clinton delivered what her campaign billed as a major foreign-policy speech, but it turned into an unrelenting bashing of Donald Trump.

Speaking in San Diego, Clinton denounced her presumed GOP rival as “temperamentally unfit” to be president, and warned that his penchant to lash out on Twitter could translate into real wars that cost American lives.

“He is not just unprepared — he is temperamentally unfit to hold an office that requires knowledge, stability and immense responsibility,” Clinton said Thursday in her 30-minute verbal assault.

“This is not someone who should ever have the nuclear codes — because it’s not hard to imagine Donald Trump leading us into a war just because somebody got under his very thin skin . . . We cannot let him roll the dice with America.”

In her fiercest campaign speech yet, Clinton unloaded a large chunk of her general election playbook against the real estate mogul.

She pushed back on Trump’s foreign-policy positions as “dangerously incoherent,” slammed his “bizarre rants, personal feuds and outright lies,” and mocked his credentials.

“He says he has foreign-policy experience because he ran the Miss Universe pageant in Russia,” Clinton said.

She touted her own national-security experience as secretary of state and senator, while denouncing Trump as too thin-skinned to withstand the pressure cooker of the Situation Room.

“He has no idea what he’d do to stop ISIS,” Clinton added. “He also refused to rule out using nuclear weapons against ISIS, which would mean mass civilian casualties.”

Crooked Hillary no longer has credibility – too much failure in office. People will not allow another four years of incompetence!

— Donald J. Trump (@realDonaldTrump) June 2, 2016

As she spoke, Trump was commenting on Twitter.

“Bad performance by Crooked Hillary Clinton! Reading poorly from the teleprompter! She doesn’t even look presidential!” Trump tweeted.