Iranian President Hassan Rouhani said on Saturday it was no time to build walls between nations and criticised steps towards cancelling world trade agreements, without naming new US President Donald Trump.

His remarks on Saturday came after Trump ordered the construction of a wall along the US-Mexico border and imposed tough new controls on travellers from seven Muslim countries, among them Iran.

"They have forgotten that the Berlin Wall collapsed many years ago. Even if there are walls between nations, they must be removed," Rouhani said at a tourism convention in Tehran.

Rouhani did not comment directly on the visa ban, but said Iran had "opened its doors" to foreign tourists since the signing of a nuclear agreement with world powers in 2015.

With more than a million Iranians living in the US, many families are deeply concerned about the implications of Trump's visa ban, which also affects citizens from Iraq, Libya, Somalia, Sudan, Syria and Yemen.

"To annul world trade accords does not help their economy and does not serve the development and blooming of the world economy," Rouhani said at the Tehran conference. "This is the day for the world to get closer through trade."

The protectionist-minded Trump formally withdrew the United States from the Trans-Pacific Partnership trade deal on Monday, fulfilling a campaign pledge to end American involvement in the 2015 pact.