A Reuters witness said several people, including African migrants, died in the attack. Guterres' spokesman, Stephane Dujarric, said further deadly air strikes had been reported elsewhere in Yemen with children among those killed.
"An airstrike on telecommunications facilities in Hodeidah has also significantly disrupted vital internet services across much of the country," Dujarric said in a statement. "The Secretary-General calls for prompt, effective and transparent investigations into these incidents to ensure accountability."
Save the Children said in a statement that three children were reportedly killed in the western city of Hodeidah.
The Saudi-led military coalition has been fighting the Iran-aligned Houthi group in Yemen since 2015. The coalition said the report of dozens of deaths on Friday would be investigated "using an internationally approved, independent process."
It has intensified air strikes on what it says are Houthi military targets after the group carried out an unprecedented assault on coalition member the United Arab Emirates on Monday and further missile and drones launches at Saudi cities.
During a news conference earlier on Friday, Guterres said: "This escalation needs to stop."
Dujarric said Guterres reminds all parties that they are obliged to "ensure that civilians are protected against the dangers arising from military operations, adhering to the principles of proportionality, distinction and precaution."
The UN Security Council condemned the Houthi attack on the UAE and other sites in Saudi Arabia in a statement on Friday after a closed-door meeting, requested by the UAE. The UAE joined the 15-member council this month for a two-year term.
Asked about the air strikes on Yemen on Friday, UAE UN Ambassador Lana Nusseibeh told reporters: "The coalition undertake to abide by international law and proportionate response in all its military operations."
US Secretary of State Antony Blinken spoke with Saudi Foreign Minister Faisal bin Farhan al Saud on Friday to reaffirm a US commitment to help Gulf allies improve their defence and underscored "the importance of mitigating civilian harm," the State Department said.
Later, Blinken said in a separate statement that the heightening of the conflict was of "great concern" to the United States and called on all sides to de-escalate.
The conflict, in which the coalition intervened after the Houthis ousted the internationally-recognised government from the capital Sanaa, has killed tens of thousands of people, displaced millions and pushed Yemen to the verge of famine.