The American government recently appealed to a number of European countries, asking them to avoid sanctioning Iran and its weapons industry.
A number of European countries have put together a serious sanctions package against Iran, due to Iran's transfer of weapons to Russia in its war against Ukraine and to terrorist organizations like the Houthis in the Middle East.
Germany, France, and Holland planned to immediately declare sanctions, especially against Iran's weapons industry and significant economic parties in the country. But the US sent them and the EU a message to not execute sanctions against Iran since they might cause escalation at this stage.
The White House still hopes for an agreement regarding its nuclear project, and they fear sanctions against the Ayatollahs may drive them away from the negotiating table.