Simon O’Connor, the spokesman for the union’s economic and monetary affairs commissioner, Olli Rehn, declined to comment on whether Mr. Rehn had taken a position on the possible impact of the Greek debt write-down on Cypriot banks.

As well as hitting Cyprus over its banks’ holdings of Greek bonds, the European Union also abruptly raised the amount of capital all European banks needed to hold in order to be considered solvent. This move, too, had good intentions — making sure that banks had a cushion to fall back on. But it helped drain confidence, the most important asset in banking.

“The bar suddenly got higher,” said Fiona Mullen, director of Sapienta Economics, a Nicosia-based consulting firm. “It was a sign of how the E.U. keeps moving the goal posts.”

Cyprus, she added, “created plenty of its own problems” and was not aided by the fact that the country’s last president, a communist who left office in February, and his central bank chief were barely on speaking terms. But decisions and perceptions formed more than 1,500 miles away in Brussels and Berlin “didn’t help and often hurt,” Ms. Mullen said.

Cyprus banks, bloated by billions of dollars from overseas, particularly from Russia, had many troubles other than Greek bonds, notably a host of unwise loans in Cyprus at the peak of a property bubble, now burst, and, critics say, to Greek companies with ties to Laiki’s former chairman, the Greek tycoon Andreas Vgenopoulos.

Mr. Kazamias, the finance minister at the time of the Greek bond write-down, said he had little idea of just how badly the move would hurt his country’s banks. “We worried but we never received any information that this was a red line” that should not be crossed, he said. The Cypriot government, he added, initially calculated that “we were in a position to cover the losses,” and it was only later, after depositors began to flee and the Cyprus economy stalled, that “we found out that this was impossible.”

But Charles H. Dallara, the lead representative for the banking industry who negotiated with European officials in 2011 in a bid to keep the losses imposed on Greek bonds as low as possible, said the writing was on the wall.