"Pfizer will continue to be disciplined on price."
Pfizer is widely expected to comeback with a sweetened offer for AstraZeneca this week, although people with knowledge of the matter said it was likely to wait until after the parliamentary hearings to make any new move.
Pfizer's bid would be the largest foreign takeover of a British firm and is opposed by many scientists and politicians, as well as AstraZeneca itself.
Parliamentary select committees cannot block corporate transactions but they can question executives ferociously, as banks, energy companies and Rupert Murdoch's News Corp. have all found out to their cost: The media coverage resulting from these firms' sessions with lawmakers confirmed them as corporate bad guys for many members of the public and placed their future dealings under even closer scrutiny.
Read MoreBig week ahead in Pfizer's fight for AstraZeneca
Pfizer already has a tarnished reputation in Britain after shutting down most of its research in southern England where Viagra was invented, with the loss of some 1,700 jobs.
Now it faces skepticism about its long-term commitment to AstraZeneca—though Read told the panel: "I'm a man of my word."
Pfizer has given a five-year commitment to complete AstraZeneca's new research center in Cambridge, retain a factory in the northwestern English town of Macclesfield and put a fifth of its research staff in Britain if the deal goes ahead.
However it has also said it could adjust those promises if circumstances changed "significantly."