No
It is unlawful to engage in “deceptive or misleading conduct in trade or commerce” - knowingly telling an untruth (i.e. lying) is both deceptive and misleading.
Advertising puffery (“whiter than white”, or “best pies in the world”) and other statements that while untrue would not mislead or deceive a reasonable person don’t count.
Outside trade or commerce - personal relationships, politics etc. - you are free to mislead or deceive as much as you can get away with.
So, if your transaction is blocked because they suspect fraud, they don’t have to tell you that (although, why wouldn’t they?), but they can’t tell you something misleading or deceptive.