With the exception of a June 11 meeting in Oslo that will feature modified events in line with social distancing rules, the season proper is now scheduled to start in Monaco on August 14.
Twelve meetings will feature, culminating in China on October 17 at a venue yet to be arranged.
The London Diamond League meeting scheduled for July 4-5 has been cancelled.
Announcing that decision, UK Athletics chief Joanna Coates said: "We must place the safety of the entire athletics family at the forefront of every decision we make during these unprecedented times and ensure we are following government advice."
The Zurich Weltklasse meeting, which had been due to form the three-day finals of the Diamond League on September 9-11, has also been scrapped.
"Despite the fact that the Swiss Federal Council has banned large events only until the end of August, staging the finals in their intended form is unrealistic," the Zurich organisers said.
The meeting in Rabat is the third to have been removed.
The Diamond League season had originally been due to start in Doha on April 17.
Athletes have been forced to recalibrate their entire season after the 2020 Tokyo Olympics were postponed by a year.
The European Athletics Championships, due to have taken place in Paris in the second half of August, have been cancelled.
Revised Diamond League Calendar
June 11 - Oslo
August 14 - Monaco
August 16 - Gateshead
August 23 - Stockholm
September 2 - Lausanne
September 4 - Brussels
September 6 - Paris (to be confirmed)
September 17 - Rome/Naples
September 19 - Shanghai
October 4 - Eugene
October 9 - Doha
October 17 - Chinese venue to be arranged. (AFP) ATAT