Business groups have welcomed Parliament voting to seek a delay to Brexit.
But the CBI said that without a “radically new approach” to Brexit, a delay was only “a stay of execution”.
The British Chambers of Commerce added that it “leaves firms with no real clarity on the future.”
The pound fell a third of a cent against the dollar immediately following the vote.
The fall follows a climb to nine-month highs against the US dollar and a nearly two-year high against the euro after a vote on Wednesday.
Currency: Pound vs dollar
The latest vote came after MPs rejected Theresa May’s withdrawal agreement for the second time and then ruled out a no-deal Brexit.
However, business groups remained sceptical about the Brexit process.
Josh Hardie, CBI deputy director-general, said: “After an exasperating few days, Parliament’s rejection of no deal and desire for an extension shows there is still some common sense in Westminster. But without a radically new approach, business fears this is simply a stay of execution.”
Dr Adam Marshall, director general of the British Chambers of Commerce (BCC), said: “Once again, businesses are left waiting for Parliament to reach a consensus on the way forward and are losing faith that they will achieve this.
“In the meantime, firms are continuing to enact their contingency plans, anxiety amongst many businesses is rising, and customers are being lost.
“Businesses, jobs, investment and our communities are still firmly in the danger zone.”
Catherine McGuinness, policy chair of The City of London Corporation said: “The clock is ticking. Further delays will mean households and businesses remain hostage to the crippling economic uncertainty that has already plagued them since the referendum.”
Tech industry body TechUK said “We remain days away from a chaotic exit from the EU.”