France, he said, had "an immigration problem" and the law was needed to reduce illegal immigration but also facilitate the integration of documented arrivals.
"It is a shield that we needed," Macron said about the law that has caused a revolt among his party's deputies, and prompted health minister Aurelien Rousseau to quit the government.
Macron told the France 5 broadcaster that the government needed "to stand by" the law "and calm the tensions."
Following 18 months of wrangling over one of the flagship reforms of Macron's second term, both chambers of parliament backed the controversial legislation on Tuesday.
Marine Le Pen's far-right National Rally, RN, endorsed the bill in a move some media dubbed a "kiss of death."
The lower house of the French parliament voted in favor of the legislation by a wide majority, with the ruling party in the end not needing the support of Marine Le Pen's far-right RN to push the bill through.
Various amendments have seen the immigration measures further tightened from when the bill was originally submitted, with the left accusing the government of caving in to pressure from the far right.
Le Pen endorsed the strengthened bill but key left-leaning members of Macron's Renaissance Party and allied factions indicated they could no longer support it, with several ministers reportedly threatening to resign.
"We can rejoice in ideological progress, an ideological victory even for the National Rally, since this is now enshrined into law as a national priority," said Le Pen, a three-time presidential candidate who leads the RN's lawmakers in parliament and is widely expected to stand again for president in 2027.
The RN had previously said it would vote against the bill or abstain. French media dubbed her surprise move a "kiss of death" for Macron's party.
The bill had been voted down without even being debated in the National Assembly last week, in a major blow to Macron.
The upper-house Senate had earlier also passed the legislation, which then went through the lower house with 349 in favor and 186 against.
Opposition!
"The immigration law will leave deep scars," said French right-wing daily Le Figaro, adding that Macron "had lost on all fronts."
Liberation, a left-wing newspaper, called it a "moral defeat" for his party.
France has a long tradition of welcoming refugees and immigrants, but a rise in the number of asylum seekers, a chronic affordable-housing shortage, and a cost-of-living crisis have worsened social tensions in the country.
A key element of the law is that social security benefits for foreigners will now be conditioned on five years of presence in France, or 30 months for those who have jobs.
Migration quotas can also now be agreed and there are measures for dual-national convicts being stripped of French nationality.
"It's a total victory for the ideas defended by Marine Le Pen," said far-right lawmaker Jean-Philippe Tanguy.
The left-wing opposition slammed the measures. The head of the Socialist deputies in the Assembly, Boris Vallaud, accused the government of "giving in to the most rancid ideas."
A hot-button issue in France, as elsewhere in Europe, immigration regularly inflames the political class.
On Wednesday, EU countries and lawmakers reached an agreement on an overhaul of the bloc's laws on handling asylum-seekers and migrants.
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