Pascal Soriot, who took over from Dave Brennan as chief executive of AstraZeneca in 2012, declined to comment on the possibility of an offer from Pfizer. He also suggested that similar deals to that announced by rivals GlaxoSmithKline and Novartis earlier in the week, where both pharma giants agreed to buy units in which they have more expertise than the other, would be more suitable for AstraZeneca.
"What you are likely to see from us is continued focus on what we do well," he said.
"It's important in our industry to become more efficient. We have tremendous pressures on all our companies."
On Thursday, AstraZeneca reported a rise in revenues but declining profits for the first quarter, as the debate over its future continued.
Revenues rose by 3 percent from the same time in 2013 to $6.4 billion, but core operating profit for the quarter was down 11 percent to $1.95 billion.
Earnings per share fell by 40 percent to $0.40 for the quarter, following the high-profile disposal of its former flagship research center near Manchester. The company's share price fell slightly in early London trading.
The company has recently become the focus of takeover speculation after it emerged that Pfizer, the biggest company in the sector, made a preliminary approach in late 2013. AstraZeneca has declined to comment on the approach.
One of its biggest attractions for an acquirer is its pipeline of new cancer drugs. AstraZeneca has recently brought forward several of these to the final stages of clinical trials.
Savvas Neophytou, analyst at Panmure Gordon, argued that AstraZeneca is on its way up whether it is taken over or not. "With pipeline improving, the stock is on a positive trajectory and investors should not be short going into the key medical conference season," he said.