At noon AEDT on Thursday, the benchmark S&P/ASX200 index was down 20.3 points, or 0.24 per cent, to 8,538.9, while the broader All Ordinaries was down 18.2 points, or 0.21 per cent, to 8,761.7.
July 9 is the next deadline for trade deal negotiations, following Mr. Trump's declaration of a 90-day pause on his reciprocal tariffs on April 9.
At midday, health care was the ASX's only sector in the green.
Energy, mining and financials were all basically flat, and the exchange's other seven sectors were in the red.
Tech was the biggest mover, dropping 1.8 per cent as Xero shed 4.6 per cent to a more than three-week low of $185.32 after the New Zealand cloud accounting company completed a $1.85 billion capital raising to buy US payments firm Melio.
In the heavyweight mining sector, BHP was down 0.1 per cent, Rio Tinto was up 0.1 per cent and Fortescue had gained 0.3 per cent.
Northern Star had dropped 3.0 per cent as the threat of war in the Middle East faded.
The yellow metal was changing hands at $US3,349 an ounce, about the same as on Wednesday.
In the financial sector, the big four banks were mixed.
ANZ was up 1.3 per cent and CBA was up 0.1 per cent - after closing at an all-time high on Wednesday - while Westpac was down 0.3 per cent and NAB had dropped 0.5 per cent.
In health care, Neuren Pharmaceuticals had climbed 9.2 per cent to $13.69 after its potential treatment for a neurodevelopmental condition called Pitt Hopkins syndrome received a US patent.
In currency, the Australian dollar was buying 65.24 US cents, from 65.03 US cents at midday on Wednesday.
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