LONDON (Reuters) -Oil prices rose on Friday after new sanctions were imposed on Iran's crude exports but were on track for a third straight week of decline, hurt by U.S. President Donald Trump's renewed trade war on China and threats of tariffs on other countries. Brent crude futures were up 42 cents, or 0.6%, at $74.71 a barrel at 1300 GMT, but were poised to fall 2.6% this week. The U.S. Treasury said on Thursday it was imposing new sanctions on a few individuals and tankers helping to ship millions of barrels of Iranian crude oil per year to China, in an incremental move to increase pressure on Tehran.