The benchmark index fell 0.34%, or 23.2 points, to 6,754.64, following a 1% fall on Friday.
Fresnillo, up 1.86%, was the biggest riser, while the London Stock Exchange, down 2.29%, was the main loser.
It came as the pound briefly hit 1.70 against the US dollar on expectations that the Bank of England could increase interest rates later this year.
"All of these remarks do suggest the tide is turning at the Bank of England," said Jane Foley, a currency strategist with Rabobank in London. "Whether that means that a hike by the end of this year is on the cards, we are not sure."
She added that Bank of England minutes, released later this week, should go some way to indicating when a rate rise might come.
Shares in the British medical company Smith and Nephew closed 0.09% down, having initially fallen 1.4% after a decision by a potential suitor, American firm Medtronic, to buy its rival Covidien instead.
The prospect of rising fuel prices pushed British Airways-owner IAG and Easyjet lower.
Outside the top tier, Majestic Wine slid nearly 4% as it reported flat profits and warned that its rate of online growth had slowed due to new entrants into the market.
(Close): Worries over tensions in Ukraine and Iraq saw the FTSE 100 drift lower for a second trading session.