Strikes severely disrupted transport, schools and other public services across France.
French workers would have to work longer before receiving a pension under the new rules _ with the nominal retirement age rising from 62 to 64. In a country with an aging population and growing life expectancy where everyone receives a state pension, Macron's government says the reform is the only way to keep the system solvent.
Unions argue the pension overhaul threatens hard-fought rights, and propose a tax on the wealthy or more payroll contributions from employers to finance the pension system. Polls suggest most French people also oppose the reform.
More than 200 rallies were staged around France on Thursday, including a large one in Paris involving all France's major unions.
Jean Paul Cachina, 56, a worker in human resources, joined the march in the French capital _ a first ever for him. "I am not here for myself,'' he said. "I am here to defend the youth and workers doing demanding jobs. I work in the construction industry sector and I'm a first hand witness of the suffering of employees.''
Many young people were among the Paris crowd, chanting "the youth is protesting. Macron you are finished.'' High school student unions had urged members to join the protests.
Nathan Arsac, 19, a student and member of the UNEF union, said: "I'm afraid of what's going to happen next. Losing our social achievements could happen so fast. I'm scared of the future when I'll be older and have to retire.''
Sylvie Bechard, a 59-year-old nurse, said she joined the march because "we, healthcare workers, are physically exhausted.''
"The only thing we have is demonstrating and to block the economy of the country,'' she added.
The economic cost of the strikes was not immediately clear. The government worries that a big show of resistance Thursday could encourage unions to continue with protracted walkouts that could hobble the economy just as France is struggling against inflation and trying to boost growth.
Police unions opposed to the retirement reform also took part in the protests, while those on duty braced for potential violence should extremist groups join the demonstrations.
Most train services around France were cancelled, including some international connections, according to the SNCF rail authority. About 20% of flights out of Paris' Orly Airport were cancelled and airlines warned of delays.
The ministry of National Education said some 34 to 42% of teachers were on strike, depending on schools.
Thierry Desassis, a retired teacher, called the government's plan "an aberration.''
"It's at 64 that you start having health problems. I'm 68 and in good health but I've started seeing doctors more often,'' he said.
The strike was also affecting some monuments. The Versailles Palace was closed on Thursday while the Eiffel Tower warned about potential disruptions and the Louvre Museum said some exhibition rooms would remain closed.
Philippe Martinez, secretary general of the CGT union, urged Macron to ``listen to the street.``
Laurent Berger, head of the CFDT union, called the reform ``unfair'' and said ``there will be other action days.''
Many French workers expressed mixed feeling about the government's plan and pointed to the complexity of the pension system.
Quentin Coelho, 27, a Red Cross employee, felt he had to work Thursday despite understanding ``most of the strikers' demands.'' With an aging population in the country, he said, raising the retirement age ``isn't an efficient strategy. If we do it now, the government could decided to raise it further in 30 or 50 years from now. We can't predict."
Coelho said he doesn't trust the government and is already saving money for his pension.
French Labor Minister Olivier Dussopt acknowledged "concerns'' prompted by the pension plans that will require workers to make "an additional effort.''
Speaking on LCI television, Dussopt justified the choice to push back the retirement age because the government rejected other options involving raising taxes _ which he said would hurt the economy and cost jobs _ or reducing pensions.
The French government is formally presenting the pension bill on Monday and it will head to Parliament next month. Its success will depend in part on the scale and duration of the strikes and protests.
Most opposition parties, including the left and the far-right, are strongly against the plan. Macron's centrist alliance lost its parliamentary majority last year, yet still has the most important group at the National Assembly, where it has a good chance of being able to ally with the conservative The Republicans party to approve the pension reforms.
Under the planned changes, workers must have worked for at least 43 years to be entitled to a full pension. For those who do not fulfil that condition, like many women who interrupted their career to raise children or those who studied for a long time and started working late, the retirement age would remain unchanged at 67.
Those who started to work early, under the age of 20, and workers with major health issues would be allowed early retirement.
Protracted strikes met Macron's last effort to raise the retirement age in 2019. He eventually withdrew it after the COVID-19 pandemic hit.
Retirement rules vary widely from country to country, making direct comparisons difficult. The official retirement age in the U.S. is now 67, and countries across Europe have been raising pension ages as populations grow older and fertility rates drop.
But opponents of Macron's reform note that, under the French system, people are already required to work more years overall than in some neighboring countries to receive a full pension.
The plan is also seen by many as endangering the welfare state that's central to French society.