"At the same time, I feel really sorry for those customers whose plans have been ruined by the Unite [trade] union's completely unjustified action," he added.
Amid growing hostility between BA and Unite, whose members are staging a total of seven days of strikes, the union claimed the cost to BA would be $149m.
"If you add together the cost of lost bookings, of revenue effectively transferred to other airlines along with BA passengers, the cost of [leased] aircraft and the cost of knock-on post-strike disruption, this is the ball-park area we are in," Unite said in a statement.
By contrast, BA said on Monday that a three-day walkout from last Saturday would cost $10.4 million a day and that an assessment of the full cost of the seven-day action could only be made after it was finished.
Talks between the two sides broke down eight days ago, on the eve of the first wave of strikes.
The Unite union accuses BA management of not being interested in finding an agreement with cabin crew.
The airline wants to save more than $90m annually through a series of cuts to pay and staffing to help cope with a fall in demand, volatile fuel prices and increased competition from low-cost carriers.
Unite argues it was not properly consulted on the changes.
BA says it had offered to modify the changes, even though they had been approved by Britain's high court, but Unite had declined to put the offer to its members to vote.
Unite has said more strikes will be scheduled after April 14 if the dispute is not resolved.
Gordon Brown, the British prime minister, has condemned the strike.
But with a general election expected to take place in May, the main opposition Conservatives have accused the government of a weak response to the strike because Unite is a major donor to Brown's ruling Labour party.