The influential CGT union called the strike after failed last-minute talks on Monday which lasted for seven hours.
Negotiations resumed yesterday but some points remained unresolved, union officials said, adding that the structure could re-open for tourists later today.
The tower normally opens at 9:00am (0700 GMT) and closes after midnight during the peak summer season that runs from June until September.
The strike by the 300-odd workers is the first since a two-day shutdown in December 2010.
The 324-metre (1,063-foot) structure attracts about seven million tourists every year.