Pfizer CEO Albert Bourla said Tuesday that uncertainty over drug tariffs planned by President Donald Trump is preventing the company from further investing in U.S. manufacturing and research and development.

Bourla's speech to the company's first-quarter earnings call was to answer questions Pfizer hopes to see from tariff negotiations that would prompt the company to increase investment in the U.S. because drug manufacturers are brave enough to impose taxes on Trump's drugs imported by the country - his administration promotes taxes on domestic manufacturing.

"If I knew there would be no tax … then in the country, there could be huge investments in R&D and manufacturing," Bra said on the phone.

"In times of uncertainty, everyone controls costs like we do, and then invests like us are very frugal so that we can prepare for our careers. That's what I want to see."

Bra noted that the tax environment that has previously promoted manufacturing abroad has "changed a lot" with the establishment of a global minimum tax rate of about 15%. He said the shift wouldn't necessarily make the U.S. more attractive, saying "investment here is not that good" without additional incentives or clarity around tariffs.

"Now (Trump) I'm sure - I know, because I talk to him - he wants to see the current tax system, especially the reduction in locally produced goods," Berra said.

Unlike other companies struggling to compete with evolving trade policies, Pfizer has not revised its full-year outlook on Tuesday. However, the company noted in its earnings release that the guidance “currently does not include any potential impacts related to future tariff and trade policy changes that we cannot predict at this time.”

But in Tuesday's earnings call, Pfizer executives said the guidance did reflect $150 million of Trump's current taxes.

"There are some tariffs today among the guidance we are not really talking about," Pfizer's chief financial officer Dave Denton said in the call.

“We are considering within our guidance range and even if these fees are incurred this year, we will continue to trend towards the top of our guidance range,” he said.