Trump said "Don't shoot the protestors or else." Iran shot the protestors. US military assets were out of position dealing with Venezuela. Now the assets are in position, the administration now feels obligated to impose "or else."

I doubt Trump's seriously seeking a nuclear deal as he (in)famously withdrew from the deal established by the Obama administration [1].

[1] https://en.wikipedia.org/wiki/United_States_withdrawal_from_...