Germany continued its sharp criticism of U.S. President Donald Trump on Sunday, saying his planned sanctions against Tehran would also make it difficult for Europeans to maintain economic incentives as part of the Iran nuclear deal.

German Foreign Minister Heiko Maas told weekly Bild am Sonntag that European countries would continue their efforts, despite Trump’s decision to withdraw from the accord, to ensure that Iran would adhere to its commitments to limit its nuclear program.

“Iran continues to signal that it’s open for talks. It’s clear that for that we have to maintain economic incentives, and that would not be easy after the U.S. decision” he said.

Maas acknowledged that they did not have the means to provide assurances for companies planning to do business with Iran.

“I don't see a simple solution to protect companies from all the risks of American sanctions. Therefore, our talks would also discuss the issue of how to make it possible to continue trade with Iran,” he said.

The foreign ministers of Germany, France and the UK -- three European signatories of the 2015 deal with Iran -- are scheduled to meet their Iranian counterpart Javad Zarif on Tuesday in Brussels.

Last week, Trump claimed that Iran had lied about its nuclear program and pulled the U.S. out of the landmark deal that world powers struck in 2015. His decision was greeted with widespread opposition, both worldwide and among many U.S. leaders.

In July 2015, the P5+1 group of countries -- China, Germany, France, Russia, the U.K. and U.S. -- signed with Iran the nuclear deal, also known as the Joint Comprehensive Plan of Action (JCPOA).

World powers agreed to lift some of the economic sanctions imposed on Iran in return for the latter agreeing to rein in its nuclear program.