Each and every one of the first Seven Ecumenical Councils are recognized as valid councils by the Catholic Church. No Roman Pontiff has ever decreed it otherwise. You will not find any Papal Bulls or any other decrees of condemnations on this point!
In fact, any truly orthodox Catholic website will always list the first seven Ecumenical Councils in the list of their 21 recognized Ecumenical Councils.
Although the Council in Trullo is not officially recognized as an "Ecumenical" Council by the Church, there is so be found no formal condemnation of the council either.
The Catholic Encyclopedia has this to say about the Council of Trullo:
Rome had recognized fifty of the Apostolic Canons, therefore the other thirty-five obtain recognition from this council, and as inspired teaching (see APOSTOLIC CANONS).
In the matter of celibacy the Greek prelates are not content to let the Roman Church follow its own discipline, but insist on making a rule (for the whole Church) that all clerics except bishops may continue in wedlock, while they excommunicate anyone who tries to separate a priest or deacon from his wife, and any cleric who leaves his wife because he is ordained (can. iii, vi, xii, xiii, xlviii).
The Eastern Orthodox churches holds this council an ecumenical one, and adds its canons to the decrees of the Fifth and Sixth Councils. in the West St. Bede calls it (De sexta mundi aetate) a "reprobate" synod, and Paul the Deacon (Hist. Lang., VI, p. 11) an "erratic" one. Dr. Fortescue rightly says (op. cit. below, p. 96) that intolerance of all other customs with the wish to make the whole Christian world conform to its own local practices has always been and still is a characteristic note of the Byzantine Church. For the attitude of the popes, substantially identical, in face of the various attempts to obtain their approval of these canons, see Hefele, "Conciliengesch." (III, 345-48).
THE COUNCIL IN TRULLO REVISITED: ECUMENISM AND THE CANON OF THE COUNCILS states that neither the Pope or his Legate signed this document. The Emperor indeed had hoped for an Ecumenical Council, but the West was not represented!
The space for the signature of “the pope of Rome,” the second
after the emperor, is indeed blank in the manuscripts, showing that the
pope did not attend the council personally or through a delegate, but
room had been made for the later papal reception (“confirmation”) of the
After the signature of “Paul the Bishop of Constantinople” in the
third place, there follow those of patriarches of Alexandria, Antioch, and
Jerusalem—disproving the assertion of certain Western polemists that
these patriarchs did not take part in the council, and that therefore it was
not ecumenical (emphasis mine). Of the 227 participants at the Trullo Council, 190 were
from the patriarchate of Constantinople; the others were the patriarch of
Alexandria, 24 Antiochians, two participants from the patriarchate of Jerusalem,
and ten bishops from Illiricum orientale. - (Page 16).
In more recent times, Pope Paul VI cited the Trullan Council (c. 13) to
confirm the tradition of the Eastern Catholic Churches regarding the
married clergy.54 And Pope John Paul II, in his apostolic constitution
promulgating the Code of Canons of the Eastern Churches, referred expressly to the first canon of Nicaea II, which confirmed the canons of
“the six holy and universal synods,” thus implicitly recognizing the Trullan
Council as the sixth ecumenical council. - (Page 22).