Google, Apple, Tesla, Uber and other tech giants expressed dismay over an executive order on immigration from President Donald Trump that bars nationals of seven Muslim-majority countries from entering the U.S.

The U.S tech industry relies on foreign engineers and other technical experts for a siginificant percentage of its workforce. The order bars entry to the U.S. for anyone from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen for 90 days.

Apple CEO Tim Cook noted in a memo to Apple employees that he was concerned about Donald Trump's executive orders limiting immigration from seven countries, and that "it is not a policy we support."

In the memo, Cook noted that there were employees that were affected by the executive orders, and that the company's human resources, legal, and security teams were in touch to support them. He also noted that the company had reached out to the White House to protest the orders.

"As I've said many times, diversity makes our team stronger. And if there's one thing I know about the people at Apple, it's the depth of our empathy and support for one another. It's as important now as it's ever been, and it will not weaken one bit. I know I can count on all of you to make sure everyone at Apple feels welcome, respected and valued.

"Apple is open. Open to everyone, no matter where they come from, which language they speak, who they love or how they worship. Our employees represent the finest talent in the world, and our team hails from every corner of the globe," Cook wrote.

Netflix CEO Reed Hastings denounced Trump's policy, call this "a very sad week." "Trump's actions are hurting Netflix employees around the world, and are so un-American it pains us all," Hastings said in a Facebook post. "Worse, these actions will make America less safe (through hatred and loss of allies) rather than more safe."

"It is time to link arms together to protect American values of freedom and opportunity," he continued. Facebook founder Mark Zuckerberg criticized the order in similar, though more carefully couched, terms on Friday .

Tesla Motors and SpaceX founder Elon Musk, who has recently appeared to be cultivating a relationship with Trump, tweeted that "many people negatively affected by this policy are strong supporters of the US" who don't "deserve to be rejected." Musk is an immigrant from South Africa.

Sergey Brin, Google co-founder and president of Alphabet, joined protesters at San Francisco International Airport as demonstrators assembled at airports across the country in opposition to President Trump's immigration order.

Google told its employees from those countries to cancel any travel plans outside the U.S. and to consult with the company's human resources department if they're not currently in the U.S., according to a company-wide note.

Google CEO Sundar Pichai told employees in the note that at least 187 Google workers could be affected by Trump's order.

Microsoft also said it is providing legal advice and assistance to its employees from the banned countries, noting they are all working in the U.S. lawfully.

Aaron Levie, Box CEO of the business collaboration company, called the ban "wrong" in strong terms.

"Throughout our history, Lyft has worked hard to create an inclusive, diverse and conscientious community where all of our drivers and passengers feel welcome and respected," CEO Logan Green told Recode. "Banning people of a particular religion from entering the U.S. is antithetical to both Lyft's and our nation's core values."

Salesforce CEO Mark Benioff called for an end to the ban on Twitter. He also retweeted a number of posts critical of the executive order, including one by Twitter board member Bret Taylor.

Slack CEO Stewart Butterfield posted a lengthy tweetstorm about the ban. "Nearly every action seems gratuitously - evil," Butterfield said of Trump's first week. He went on to describe how his grandparents had found refuge in America. "We are all brothers and sisters," he said.

Uber pledged to compensate drivers stuck overseas because of Trump's ban. "This ban will impact many innocent people - an issue that I will raise this coming Friday when I go to Washington for President Trump's first business advisory group meeting," CEO Travis Kalanick said in a Facebook post.

Mozilla CEO Chris Beard: "It's a bad precedent, ignores history, and is likely to do more lasting harm than good."

"We share the concerns about the impact of the executive order on our employees from the listed countries, all of whom have been in the United States lawfully, and we're actively working with them to provide legal advice and assistance," said a Microsoft spokesperson. CEO Satya Nadella also posted a memo from company president and chief legal officer Brad Smith.

Amazon. Amazon acknowledged that the immigration ban is a thing that definitely exists, and in a message to employees, offered "contingency plans" to employees affected.

"From the very beginning, Amazon has been committed to equal rights, tolerance and diversity - and we always will be," wrote VP of human resources Beth Galetti. "As we've grown the company, we've worked hard to attract talented people from all over the world, and we believe this is one of the things that makes Amazon great - a diverse workforce helps us build better products for customers."

The tech industry may be bracing for further immigration-related hits. Leaks of draft executive orders, suggest that Trump might also revamp the H1-B program that lets Silicon Valley bring foreigners with technical skills to the U.S. for three to six years.

While the tech industry insists the H1-B program is vital, it has drawn fire for allegedly disadvantaging American programmers and engineers, especially given that the visas are widely used by outsourcing firms.