Michel Barnier, the European Union financial services chief, urged U.S. Treasury Secretary Jacob J. Lew to seek changes to draft rules on swaps and the treatment of EU bank units, saying they may undermine efforts to clinch a trade pact, said two people familiar with the talks.

Barnier told Lew that EU and U.S. moves to begin negotiations on a free-trade deal made revising the measures more urgent, according to the people who asked not to be cited by name because the discussions are private. Lew and Barnier, meeting in Brussels yesterday, agreed to further discussions on the measures, the people said.

The two agreed to "stay in close and regular contact and strengthen the U.S.-EU financial market and regulatory dialog," according to a joint statement issued by their offices. Lew raised concerns at the meeting that plans by some EU nations to implement a common tax on financial transactions would lead to charges being imposed on U.S.-based companies, the people said.