In an escalation of a trade war that has angered US allies and rattled investors, Trump announced the latest tariffs in separate letters to European Commission President Ursula von der Leyen and Mexican President Claudia Sheinbaum on Saturday.
The EU and Mexico, both among the largest US trading partners responded by calling the tariffs unfair and disruptive while pledging to continue to negotiate with the US for a broader trade deal before the deadline.
Mexican President Claudia Sheinbaum said she was sure an agreement can be reached.
"I've always said that in these cases, what you have to do is keep a cool head to face any problem," Sheinbaum said at an event in the Mexican state of Sonora.
"(But) there's something that's never negotiable: the sovereignty of our country," she said.
Trump sent similar letters to 23 other trading partners this week, including Canada, Japan and Brazil, setting blanket tariff rates ranging from 20 per cent up to 50 per cent, as well as a 50 per cent tariff on copper.
The US president said the 30 per cent rate was "separate from all sectoral tariffs", indicating 50 per cent levies on steel and aluminium imports and a 25 per cent tariff on auto imports would remain.
The August 1 deadline gives the targeted countries time to negotiate.
Some investors and economists have also noted Trump's pattern of backing off his tariff threats.
The spate of letters showed Trump has returned to the aggressive trade posture that he took in April when he announced a slew of reciprocal tariffs against trading partners that sent markets tumbling before the White House delayed implementation.
But with the stock market recently hitting record highs and the US economy still resilient, Trump is showing no signs of slowing down his trade war.
He promised to use the 90-day delay in April to strike dozens of new trade deals, but has only secured framework agreements with Britain, China and Vietnam. The EU has hoped to reach a comprehensive trade agreement with the US for the 27-country bloc.
Trump's letter to the EU included a demand that Europe drop its own tariffs.
"The European Union will allow complete, open Market Access to the United States, with no Tariff being charged to us, in an attempt to reduce the large Trade Deficit," he wrote.
Von der Leyen said the 30 per cent tariffs "would disrupt essential transatlantic supply chains, to the detriment of businesses, consumers and patients on both sides of the Atlantic".
The EU "will take all necessary steps to safeguard EU interests, including the adoption of proportionate countermeasures if required", she said.
Mexico's economy ministry said "it was unfair treatment".
Mexico's proposed tariff level is lower than Canada's 35 per cent, with both letters citing fentanyl flows even though government data shows the amount of the drug seized at the Mexican border is significantly higher than the Canadian border.
"Mexico has been helping me secure the border, BUT, what Mexico has done, is not enough. Mexico still has not stopped the Cartels who are trying to turn all of North America into a Narco-Trafficking Playground," Trump wrote.
Mexico sends more than 80 per cent of its total exported goods to the US and free trade with its northern neighbour drove Mexico to become the top US trading partner in 2023.
The EU had initially hoped to strike a comprehensive trade agreement but more recently had scaled back its ambitions and shifted toward securing a broader framework deal similar to the one Britain brokered that leaves details to be negotiated.
The bloc is under conflicting pressures as powerhouse Germany urged a quick deal to safeguard its industry, while other EU members, such as France, have said EU negotiators should not cave into a one-sided deal on US terms.
Bernd Lange, the head of the European Parliament's trade committee, said Brussels should enact countermeasures as soon as Monday.
"This is a slap in the face for the negotiations. This is no way to deal with a key trading partner," Lange told Reuters.
