However, a 32% jump in Peppa Pig owner Entertainment One after agreeing to be bought by U.S. toy maker Hasbro lifted the UK midcap index.
The FTSE 100 shed 0.5% after enjoying a recovery for most of the day, as a tweet from Trump about U.S.-China trade just minutes before the closing bell sharply raised concerns over international trade.
The FTSE 250 <.FTMC> ended 0.2% higher.
Oil majors Shell and BP were the worst hit after Trump said U.S. companies should "immediately start looking for an alternative to China", after Beijing officials earlier retaliated by imposing tariffs on $75 billion of U.S. goods.
Asia-focused financials and miners, who count on China as it is the world's top metals consumer, were also weaker.
Fears about how the trade dispute would affect the global economy and the risk of an impending recession have put the main index on track for its biggest monthly loss in four years.
The FTSE 100's initial gains were brought on by U.S. Federal Reserve Chairman Jerome Powell's reassurance that the central bank will "act as appropriate" to keep the current economic expansion on track.
"Powell kept the door open for further stimulus, but we will not see it as quickly as markets may have initially expected," Oanda analyst Edward Moya said.
The FTSE 100 had been dragged into the red on Thursday when the Fed's minutes showed divisions on future monetary policy, while a rally in the pound hit blue-chip overseas earners.
Among individual stocks, Entertainment One shares surged to a life high at 579 pence, surpassing the 560p a share deal agreed with Hasbro in a sign that investors see a chance of a counter offer.
Woodford Patient Capital Trust, the listed fund run by money manager Neil Woodford, tumbled to an all-time low after the trust's administrator said it would cut the valuation of one of its biggest holdings. The stock, however, clawed back some of the initial losses to end down 1.4%.
(Reporting by Muvija M in Bengaluru; Editing by Arun Koyyur and David Holmes)
By Muvija M and Indranil Sarkar