China's slowing growth is not good for anybody but it will not affect U.S. efforts to build business ties, U.S. Commerce Secretary Penny Pritzker said on Wednesday after Beijing announced its weakest quarter of growth in six years.

Pritzker, leading a trade mission to China with more than 20 U.S. companies, told reporters she believed the Chinese leadership saw opportunity in the "new normal" of slower gross domestic product expansion to invest in sustainable, long-term growth.

Pritzker met Chinese officials in Beijing before travelling to Shanghai.

"The fact that China is not growing as fast as it would like, that's not good for anybody. But that has not changed our engagement with the Chinese, because we are in this for the long haul and our businesses are in this for the long haul," she told reporters.

"As China is adapting they have the opportunity to change the way they are doing business and we are hearing that from Chinese leadership."

China's GDP grew an annual 7.0 percent in the first quarter — its slowest pace since 2009 — slowing from 7.3 percent in the fourth quarter of 2014, China's statistics bureau said earlier.

The three-city trade mission, focused largely on green technology, comes amid trade frictions with China over issues including solar equipment and other high tech gear.

On Tuesday, the Wall Street Journal quoted unidentified sources as saying Premier Li Keqiang had urged Pritzker and other visiting U.S. officials to drop limits on high-tech exports or it would seek alternatives from Russia or other countries.

Pritzker defended a February decision by the Department of Commerce's Bureau of Industry and Security to bar exports of certain items to four Chinese entities she said were suspected of producing supercomputers for "nuclear explosive activities".

"The U.S. has a long-standing policy against allowing the export to most countries, including China, of items that are used for nuclear explosive activities. The entities that were put on that list, they can still apply for a license for those exports and they can appeal," Pritzker told reporters when asked about the report.

"But we have to protect our national security ... In looking at the items that have dual use, we make sure that they are not going to be used for purposes that could hurt our national security."