"The situation is serious. The rise of tensions could lead to accidents," Le Drian told reporters when asked about the risk of a wider Middle East war, Reuters reported.
US President Donald Trump withdrew the United States last year from the 2015 deal between Iran and world powers to curb its nuclear program in return for relief from economic sanctions, to the dismay of other signatories France, Britain, Germany, Russia and China.
Washington has since tightened sanctions to block Iran's oil exports and other benefits accruing from the deal. After more than a year of “strategic patience,” Tehran responded by enriching uranium beyond set limits and threatening to restart deactivated centrifuges and ramp up enrichment well above the level deemed normal for electricity generation.
Tensions have also risen as Washington has blamed Iran for several attacks on oil tankers and Tehran shot down a US spy drone, prompting President Donald Trump to order airstrikes that he called off only minutes before impact.
Iran rejected the US allegation that it was behind the oil tanker attacks and said the US drone was shot down after violating Iranian airspace despite repeated warnings.
"The fact Iran has decided to pull back from some of its engagements on nuclear proliferation is an additional worry. It is a bad decision, a bad reaction to another bad decision, that of the US withdrawal from the nuclear deal a year ago," he said, arriving for Paris's annual Bastille Day military parade.
The European powers do not support Trump's sanctions squeeze on Iran, aimed at forcing it into negotiations on stricter nuclear limits and other security concessions, but have been unable to come up with ways to allow Iran to avert them.
"No one wants a war. I've noticed that everyone is saying they don't want to go to the summit of the escalation. Neither (Iranian) President Rouhani, nor President Trump.... But here there are elements of escalation that are worrisome," Le Drian said.
"Iran gains nothing from withdrawing from its engagement (with nuclear deal). The US also gains nothing…, so it is important that de-escalation measures are taken to ease the tensions."