All three terminals are operated by Elengy, a subsidiary of the French gas operator GRTgaz.
During the strike, gas will not be supplied to the GRTgaz network, LNG tankers will not be unloaded and transportation tank containers will not be filled, the French broadcaster reported.
The CGT said earlier that the trade unions intended "to bring the French economy to its knees" if the government did not withdraw the pension reform project.
On Friday, workers at French nuclear power plants also launched an indefinite strike against pension reform.
In January, French Prime Minister Elisabeth Borne unveiled a draft of the controversial pension reform that the government plans to adopt in 2023. Under the initiative, the French authorities intend to gradually raise the retirement age in the country by three months a year from September 1, 2023. By 2030, the retirement age will reach 64.
The reform has caused a wave of protests in the French society. Since Borne's announcement, five nationwide demonstrations against the reform have already taken place in France. The first two, held on January 19 and 31, gathered over 1 million people nationwide. The next demonstration is scheduled for March 7 amid strikes in almost all sectors of the economy.