The deal was reached with assistance from acting US secretary of labour Julie Su. The parties decided not to release details of the agreement now, both said in a joint press release.
The agreement is subject to ratification by both parties.
"The tentative agreement delivers important stability for workers, for employers and for our country's supply chain," Su said in a statement.
"The tentative agreement between the ILWU and the PMA brings the stability and confidence that customers have been seeking," Port of Los Angeles executive director Gene Seroka tweeted.
The earlier contract between the two sides expired on July 1 last year. Port workers have been working without a contract since then.
Fibre2Fashion News Desk (DS)