"Families seeking refuge in the US already endure emotional and physical stress, which is only exacerbated when they are separated from one another", AMA's chief executive officer Dr. James Madara writes in a letter.
But he added that the policy "continues to be a zero tolerance ..."
During the meeting, the AMA heard from delegates who said the administration's policy "will do great harm to children and their parents or caregivers, who felt compelled to make a risky and uncertain journey because of safety concerns in their own countries".
House Republicans were reportedly working on a revised plan that would mean children would be detained for longer than is now allowed but kept with their parents, the Associated Press reports.
Babies and toddlers have been sent to three "tender age" shelters maintained by the Department of Health and Human Services, the Associated Press news agency reports.
President Donald Trump says he'll be signing something "in a little while" to address the spike in the number of migrant children being separated from their families at the border.
House Republican leaders scrambled to produce a revised version of a broader immigration bill to include a provision to resolve the situation of family separations.
The children are classified as unaccompanied minors, a legal term generally used for children who cross the border alone and have a possible sponsor in the USA willing to care for them. It also calls into question numerous administration's recent claims about the basis of the "zero tolerance" policy that was announced by Attorney General Jeff Sessions in April.
Obama later criticized the policy that has resulted in thousands of families being separated at the U.S. -Mexico border, saying that watching these families broken apart in real time poses a very simple question to Americans.
Trump had tweeted earlier Wednesday, "It's the Democrats fault, they won't give us the votes needed to pass good immigration legislation".
Melania Trump's jacket: ‘I really don't care. Do U?'
Count me among the Jacket Truthers: it was no accident. "She wanted to see everything for herself", Grisham said. But Trump's fashion has often played a leading role during her tenure as first lady.
'Our immigration laws are the weakest and worst anywhere in the world, and the Dems will do anything not to change them & to obstruct-want open borders which means crime'.
The "something" will be an executive order, Trump said at a meeting with GOP lawmakers at the White House, and he will sign it before departing for Minnesota, where he is scheduled to speak at a rally Wednesday evening.
Democrats welcomed Trump's apparent change of course but said he had only himself to blame.
Trump said his daughter Ivanka also spoke with him several times to express her concerns. I feel very strongly about it.
Migrant children can not be held with their parents, and are kept in separate facilities maintained by the Department of Health and Human Services. Female suburban voters are considered crucial in deciding control of Congress this fall.
The separations began after Attorney-General Jeff Sessions announced in April that all immigrants apprehended while crossing the US-Mexico border illegally should be criminally prosecuted.
"Under current law, we have only two policy options to respond to this massive crisis. People haven't dealt with it, and we are dealing with it".
"Some governments are working on it, and people have to be settled in the best possible way, but creating psychosis is not the cure", Pope Francis said. This is wrong. This is not something that we agree with.
An administration official with knowledge of the plan indicated that the Trump administration was anticipating lawsuits and preparing to litigate Flores in court, particularly if lawmakers fail to approve a legislative fix.
The second-ranking Senate Republican, John Cornyn, said they're proposing a "humane, safe and secure family facility" where parents and children who are minors could be detained together. The House leaders still hope to have votes on both bills on Thursday. "Do we look away, or do we choose to see something of ourselves and our children?" "We are keeping the family together".
Just the day before, Trump had claimed his administration's hands were tied without congressional action.