NEW YORK (CBSNewYork/AP) — Immigration activists protested outside of Trump Tower in Manhattan Tuesday as the president defended his decision to phase out the Deferred Action for Childhood Arrivals program, which protects those brought into the country illegally as children.

Congress now has 6 months to legalize DACA (something the Obama Administration was unable to do). If they can't, I will revisit this issue! — Donald J. Trump (@realDonaldTrump) September 6, 2017

The protest began with a march down Fifth Avenue and grew to about 400 people. Some protesters cried as they held hands during a sit-in on the pavement.

Others stood on the sidelines, chanting loudly and waving signs. They yelled “undocumented — unafraid.”

One 24-year-old woman who lives and works in Manhattan says she was brought to this country from Mexico when she was 4 years old and is the only member of her family who was protected by DACA.

“I don’t consider Mexico my home,” she told WCBS 880’s Marla Diamond. “Home is here in New York.”

There were a dozen arrests as some of the protesters blocked traffic at Fifth Avenue and 56th Street around 11:30 a.m., 1010 WINS’ Al Jones reported. More people were handcuffed during a second sit-in outside Trump Tower about two hours later.

In all, 34 people were arrested.

White House spokeswoman Sarah Huckabee Sanders said Trump’s action to wind down DACA was “the responsible and constitutional step of announcing the administration will be phasing out the program.”

“The president made the best decision in light of the fact that the system set up by the Obama administration [was] in clear violation of federal law,” Sanders said. “DACA was initiated after Congress explicitly rejected the same proposal in legislative form.”

Calling it an “open-ended immigration law,” Attorney General Jeff Sessions announced earlier Tuesday that DACA was “being rescinded.”

“The Department of Homeland Security should begin an orderly, lawful wind down, including the cancellation of the memo that authorized the program,” he said.

Sessions said DACA was an “overreach of the executive branch” that “contributed to a surge of minors at the southern border that yielded terrible humanitarian consequences.”

The attorney general said the U.S. needs to have a lawful immigration that “serves the national interest.”

“The nation must set and enforce a limit on how many immigrants we admit each year and that means all cannot be accepted,” he said. “This does not mean they are bad people or that our nation disrespects or demeans them in any way.”

The executive order, enacted by the Obama administration in 2012, protects about 800,000 young immigrants who were brought to the United States by their undocumented parents, allowing the so-called “Dreamers” to enroll in the program and attend school and get work permits that are renewable every two years.

The administration will phase out the program by allowing current permits to expire, CBS2’s Dick Brennan reported. New permit requests, which have already been submitted, will be considered on a case-by-case basis.

The end of the program is expected to have a six-month delay to give Congress time to decide if it wants to address the status of the law. Details of the changes were not clear, including what would happen if lawmakers failed to pass a measure by the deadline.

The White House indicated that it wants legislation that would provide comprehensive immigration reform, which has proven difficult to pass so far.

“I have a love for these people, and hopefully now Congress will be able to help them and do it properly,” Trump said Tuesday afternoon, defending his decision. “In speaking to members of Congress, they want to be able to do something and do it right. And really we have no choice. We have to be able to do something, and I think it’s going to work out very well. And long-term, it’s going to be the right solution.”

In an earlier statement, the president said he is “not going to just cut DACA off, but rather provide a window of opportunity for Congress to finally act.”

“I do not favor punishing children, most of whom are now adults, for the actions of their parents,” he said. “But we must also recognize that we are nation of opportunity because we are a nation of laws.”

He said officials from 10 states are suing over the program, “requiring my administration to make a decision regarding its legality.”

“The Attorney General of the United States, the Attorneys General of many states, and virtually all other top legal experts have advised that the program is unlawful and unconstitutional and cannot be successfully defended in court,” Trump said.

He said the administration’s enforcement priorities “remain unchanged” and said he has advised the Department of Homeland Security that “DACA recipients are not enforcement priorities unless they are criminals, are involved in criminal activity, or are members of a gang.”

The president said he looks forward to working with both Republicans and Democrats in Congress to “finally address all of these issues in a manner that puts the hardworking citizens of our country first.”

“As I’ve said before, we will resolve the DACA issue with heart and compassion – but through the lawful Democratic process – while at the same time ensuring that any immigration reform we adopt provides enduring benefits for the American citizens we were elected to serve,” Trump said. “We must also have heart and compassion for unemployed, struggling, and forgotten Americans.”

On Twitter before the officials announcement Tuesday morning, the president said: “Congress, get ready to do your job – DACA!”

Congress, get ready to do your job – DACA! — Donald J. Trump (@realDonaldTrump) September 5, 2017

But the move triggered a stinging response from former President Barack Obama, who said in a statement, “To target these young people is wrong… It is self-defeating, and it is cruel.”

Some Republicans and most Democrats argued DACA recipients need to be protected.

“To remove them from the country, to split up families like this, is just not the way we ought to go,” said Republican Arizona Sen. Jeff Flake.

“Democrats will do everything we can to prevent President Trump’s terribly wrong order from becoming reality,” Senate Minority Leader Chuck Schumer said.

But in a bipartisan move, both Republican Sen. Lindsay Graham and Democratic Sen. Richard Durban agreed Congress needs to act now.

“We need to pass, in this month of September, a Dream act — a permanent law in this country — that says these young people will have their chance to become part of America’s future,” Durban said.

To the Dreamers of New York City:

We stand with you. We will fight for you.

In solidarity, New York City pic.twitter.com/fhOYD3no7x — NYC Mayor's Office (@NYCMayorsOffice) September 5, 2017

Mayor Bill de Blasio’s office put out a statement on Twitter.

“We are working with Cities For Action to lead mayors from across the country in a push for Congressional action to protect you, and we are prepared to take legal action to protect DACA,” the statement said. “We have your back. New York City is still your home.”

Democratic New York Gov. Andrew Cuomo says about 42,000 New Yorkers would be affected. He has threatened to sue to protect Dreamers in the state.

“It’s anti-New York,” said Cuomo. “It’s anti-American.”

In New Jersey, DACA affects about 22,000 people.

WCBS 880’s Mike Smeltz visited the New York Immigration Coalition headquarters in Midtown Tuesday, where he heard from DACA recipient Flora Reyes.

“We have come out of the shadows, only to become even in more danger,” she said.

Reyes is the oldest of six children. When her father left, she was able to use her DACA status to get a job to help take care of her siblings.

“I’m not sure how I will go home later today and explain to my mom that the help I had been providing her is not there any longer,” she said, with tears falling down her cheek.

Advocates called on Congress to create a system where Dreamers can stay in the United States and not have to retreat to the shadows, because not doing so, they said, would forever destroy what the American Dream is all about, Smeltz reported.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)