The US Justice Department says it will protect clinics that perform abortions in Texas, a state with a near-total ban on voluntary pregnancy terminations.
The department said it would “provide support from federal law enforcement” when a clinic, reproductive health centre or patient was “under attack”.
A new Texas law bans abortions from as early as six weeks into pregnancy.
Doctors and women’s rights groups have criticised the legislation, known as SB8, that took effect last week.
The so-called “Heartbeat Act” was signed into law by Texas Governor Greg Abbott in May.
The law, one of the most restrictive in the country, bans abortions after the detection of what anti-abortion campaigners call a foetal heartbeat, something medical authorities say is misleading.
It also gives any individual the right to sue doctors who perform an abortion past the six-week point.
The law took effect after the Supreme Court did not respond to an emergency appeal by abortion providers.
“We will not tolerate violence against those seeking to obtain or provide reproductive health services, physical obstruction or property damage in violation of the FACE Act,” US Attorney General Merrick Garland said in a statement on Monday.
The FACE (Freedom of Access to Clinic Entrances) Act took effect in 1994. It prohibits any form of threatening or violent behaviour towards anyone obtaining reproductive health services, typically an abortion.
In the statement, Mr Garland said his department would enforce FACE, while it “urgently explores all options to challenge Texas SB8 in order to protect the constitutional rights of women and other persons”.
How do Americans feel about abortion rights?
Abortion has long been one of the country’s most contentious social issues. However, polls from the Pew Research Center indicate nearly six in 10 Americans believe abortion should be legal in all or most cases.
This number has remained relatively stable over the past two decades, but masks a partisan divide: only 35% of Republicans support that position.
In conservative Texas, an April poll found nearly half of the state’s voters support a six-week ban on abortions.