The official death toll in Iran from the coronavirus disease has risen to 1,135, after 147 new deaths were reported in the past 24 hours.
Another 1,192 cases have also been confirmed, bringing the total to 17,361 – the third highest in the world.
Despite that, the deputy health minister warned that some Iranians were still not taking the disease seriously.
The World Health Organization's (WHO) Middle East chief has called on countries to share more information.
Dr Ahmed Al Mandhari said the agency's teams had observed "uneven approaches across the region", adding that much more ought to be done.
"The countries that have made the most progress are those that have engaged all ministries and sectors effectively," he told a briefing in Cairo.
"They are the ones that are providing accurate, transparent and timely information for their people about the current status of the pandemic, the actions being taken, and the measures individuals can take themselves."
He warned that the disease could only be controlled if experts had the information that allowed them to understand its dynamics in the region.
"Unfortunately, even today, as the situation is becoming critical, information on cases is insufficiently communicated by countries to WHO," he said.
Dr Mandhari said a total of 18,000 confirmed cases of Covid-19 and more than 1,100 related deaths had been reported across the WHO's Eastern Mediterranean Region, which comprises 21 member states and the Palestinian territories.
Almost all of the cases and deaths have been reported by Iran or been linked to it.
At a televised news conference on Wednesday, Iranian Deputy Health Minister Alireza Raisi lamented the response of some people to the outbreak.
"Now everyone knows about this disease, and what is very strange is that some don't take it seriously," he said. "If people help, we can control it, and if not, then expect it to last more than two months."
Mr Raisi complained that Tehran's bazaars were "busy" and that people were travelling in their cars despite a religious ruling from Supreme Leader Ayatollah Ali Khamenei forbidding "unnecessary" travel.
"Just be patient for these two weeks so that, God willing, we can overcome this."
Some Iranians have reportedly been trying to leave major cities ahead of Nowruz, the Persian New Year holiday, which begins on Friday and lasts until early April.
Also on Wednesday, President Hassan Rouhani defended his government's response since the first cases of Covid-19 were reported four weeks ago.
It has been criticised for only closing this week the Shia Muslim shrines in Qom – the initial epicentre of the outbreak – and Mashhad that are sites of pilgrimage.
Senior clerics had argued that the shrines should be kept open, and on Monday night crowds protesting against the closures forced their way into them.
"It was difficult of course to shut down mosques and holy sites, but we did it. It was a religious duty to do it," Mr Rouhani told a cabinet meeting.
The president also insisted that the government had been "straightforward" about the scale of the outbreak, and spoken to people with "no delay".
Health experts believe the number of cases in Iran may be significantly underreported due to testing being restricted to severe cases.
Dr Rick Brennan of the WHO's Emergencies Programme told Reuters news agency that the number of cases reported could represent only about a fifth of the actual number. He predicted that the figure would go up once testing was stepped up.