Sir Sam Mendes says opening theatres with social distancing will be like “pouring money down the drain”.
Live indoor theatre and concerts can resume with the measures in place from the start of next month.
But the Bond filmmaker told BBC Radio 4’s Today programme that “any theatre has to run at 60%, 70% capacity to even break even”.
He added: “So to run at 30% capacity … basically means pouring money down the drain, money which is not there.”
Sir Sam wants theatres to reopen without social distancing at the end of the year.
“I’m not arguing that they should reopen with no social distancing now,” he told Today.
“But there has to be a ‘no earlier than’ date – my suggestion is that should be early December, which gives theatres time to plan.”
He said it would be “up to the audience on whether they want to take the risk”, adding that “at the moment there’s a risk just leaving the house…”
“How is it different from sitting next to someone in a metal tube for eight hours in a plane? It’s not different, it’s a matter of personal choice.”
A fund set up by Sir Sam to help workers in the theatre industry has raised £1.6 million.
The director of films such as Skyfall and 1917, and plays including The Lehman Trilogy and Charlie And The Chocolate Factory, said the money will be used to support 1,600 freelancers.
However, almost 4,000 people have applied for support from the Theatre Artists Fund in one week.
Stars including Imelda Staunton, Benedict Cumberbatch, Eddie Redmayne, Colin Firth and Hugh Bonneville have donated to the fund, which was established with a £500,000 donation from streaming giant Netflix.
Sir Sam urged others to “come forward and show their support in order to help those in need”.
The Government has previously announced a £1.57 billion support package for the arts, with music venues, theatres, museums, galleries, independent cinemas and heritage sites eligible for emergency grants and loans.