Over 50% of entrepreneurs said they have put off making important business calls over the last year in case they made a mistake, according to the bank, which spoke to 1,000 small firms.
Barclays described these cautious companies as "boffs" - or businesses overcome by fear of failure - and said that almost half admit this anxiety has or could prevent their business from growing.
Some 18% admitted to playing it safe with a day-to-day focus, and over a quarter admitted that economic uncertainty has made them more hesitant about long-term decisions, the bank said.
And it is not just economic issues that weigh on the minds of the businesspeople, Barclays added - with cash flow issues, increased competition and regulation also driving these fears.
Although younger entrepreneurs, between the ages of 25 and 34, were much more willing to push themselves out of their comfort zone when it comes to making decisions, the research found.
The managing director of Barclays Business Banking, Sue Hayes, said fear of getting decision wrong is "only natural".
"It can feel like you are taking a big risk - whether that is decisions about staff, products, finance or even your marketing strategy," she said.
"Despite the tough external environment, there are many opportunities to be seized upon and the ability to make important decisions is vital to the growth of all businesses and the overall UK economy."
The research comes as a separate survey into employment indicates an increase in business confidence when it comes to hiring new staff.
The number of permanent jobs increased for first time since May and at the fastest rate in 17 months, according to KPMG's Report on Jobs.
More confident employers advertising more roles and increasingly willing candidates helped drive the rise, it said.
And temporary positions also increased - for the third month running - with growth accelerating to the sharpest pace for one-and-a-half years.
KPMG's head of business services Bernard Brown described the findings as "good news".
"In the context of jobs being filled at the fastest rate for nearly 18 months, we seem to be stepping in the right direction - something that was barely thought possible just a few short months ago," he said.
"It may not be leaps and bounds yet, in terms of progress, but these are the largest strides for some time and should not go un-noticed."
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